TOEFL.READING.E01.THE ORIGINS OF THEATER

In seeking to describe the origins of theater, one must rely primarily on speculation, since there is little concrete evidence on which to draw. The most widely accepted theory, championed by anthropologists in the late nineteenth and early twentieth centuries, envisions theater as emerging out of myth and ritual. The process perceived by these anthropologists may be summarized briefly. During the early stages of its development, a society becomes aware of forces that appear to influence or control its food supply and well-being. Having little understanding of natural causes, it attributes both desirable and undesirable occurrences to supernatural or magical forces, and it searches for means to win the favor of these forces. Perceiving an apparent connection between certain actions performed by the group and the result it desires, the group repeats, refines and formalizes those actions into fixed ceremonies, or rituals.
Stories (myths) may then grow up around a ritual. Frequently the myths include representatives of those supernatural forces that the rites celebrate or hope to influence. Performers may wear costumes and masks to represent the mythical characters or supernatural forces in the rituals or in accompanying celebrations. As a person becomes more sophisticated, its conceptions of supernatural forces and causal relationships may change. As a result, it may abandon or modify some rites. But the myths that have grown up around the rites may continue as part of the group’s oral tradition and may even come to be acted out under conditions divorced from these rites. When this occurs, the first step has been taken toward theater as an autonomous activity, and thereafter entertainment and aesthetic values may gradually replace the former mystical and socially efficacious concerns.
Although origin in ritual has long been the most popular, it is by no means the only theory about how the theater came into being.Storytelling has been proposed as one alternative.Under this theory, relating and listening to stories are seen as fundamental human pleasures.Thus, the recalling of an event (a hunt, battle, or other feat) is elaborated through the narrator’s pantomime and impersonation and eventually through each role being assumed by a different person.
A closely related theory sees theater as evolving out of dances that are primarily pantomimic, rhythmical or gymnastic, or from imitations of animal noises and sounds. Admiration for the performer’s skill, virtuosity, and grace are seen as motivation for elaborating the activities into fully realized theatrical performances.
In addition to exploring the possible antecedents of theater, scholars have also theorized about the motives that led people to develop theater. Why did theater develop, and why was it valued after it ceased to fulfill the function of ritual? Most answers fall back on the theories about the human mind and basic human needs. One, set forth by Aristotle in the fourth century B.C., sees humans as naturally imitative—as taking pleasure in imitating persons, things, and actions and in seeing such imitations. Another, advanced in the twentieth century, suggests that humans have a gift for fantasy, through which they seek to reshape reality into more satisfying forms than those encountered in daily life. Thus, fantasy or fiction (of which drama is one form) permits people to objectify their anxieties and fears, confront them, and fulfill their hopes in fiction if not fact. The theater, then, is one tool whereby people define and understand their world or escape from unpleasant realities.
But neither the human imitative instinct nor a penchant for fantasy by itself leads to an autonomous theater. Therefore, additional explanations are needed. One necessary condition seems to be a somewhat detached view of human problems. For example, one sign of this condition is the appearance of the comic vision, since comedy requires sufficient detachment to view some deviations from social norms as ridiculous rather than as serious threats to the welfare of the entire group. Another condition that contributes to the development of autonomous theater is the emergence of the aesthetic sense. For example, some early societies ceased to consider certain rites essential to their well-being and abandoned them, nevertheless, they retained as parts of their oral tradition the myths that had grown up around the rites and admired them for their artistic qualities rather than for their religious usefulness.

TOEFL.READING.E01.Groundwater

Groundwater is the word used to describe water that saturates the ground, filling all the available spaces. By far the most abundant type of groundwater is meteoric water; this is the groundwater that circulates as part of the water cycle. Ordinary meteoric water is water that has soaked into the ground from the surface, from precipitation (rain and snow) and from lakes and streams. There it remains, sometimes for long periods, before emerging at the surface again. At first thought it seems incredible that there can be enough space in the "solid" ground underfoot to hold all this water.
The necessary space is there, however, in many forms. The commonest spaces are those among the particles—sand grains and tiny pebbles—of loose, unconsolidated sand and gravel. Beds of this material, out of sight beneath the soil, are common. They are found wherever fast rivers carrying loads of coarse sediment once flowed. For example, as the great ice sheets that covered North America during the last ice age steadily melted away, huge volumes of water flowed from them. The water was always laden with pebbles, gravel, and sand, known as glacial outwash, that was deposited as the flow slowed down.
The same thing happens to this day, though on a smaller scale, wherever a sediment-laden river or stream emerges from a mountain valley onto relatively flat land, dropping its load as the current slows: the water usually spreads out fanwise, depositing the sediment in the form of a smooth, fan-shaped slope. Sediments are also dropped where a river slows on entering a lake or the sea, the deposited sediments are on a lake floor or the seafloor at first, but will be located inland at some future date, when the sea level falls or the land rises; such beds are sometimes thousands of meters thick.
In lowland country almost any spot on the ground may overlie what was once the bed of a river that has since become buried by soil; if they are now below the water’s upper surface (the water table), the gravels and sands of the former riverbed, and its sandbars, will be saturated with groundwater.
So much for unconsolidated sediments. Consolidated (or cemented) sediments, too, contain millions of minute water-holding pores. This is because the gaps among the original grains are often not totally plugged with cementing chemicals; also, parts of the original grains may become dissolved by percolating groundwater, either while consolidation is taking place or at any time afterwards. The result is that sandstone, for example, can be as porous as the loose sand from which it was formed.
Thus a proportion of the total volume of any sediment, loose or cemented, consists of empty space. Most crystalline rocks are much more solid; a common exception is basalt, a form of solidified volcanic lava, which is sometimes full of tiny bubbles that make it very porous.
The proportion of empty space in a rock is known as its porosity. But note that porosity is not the same as permeability, which measures the ease with which water can flow through a material; this depends on the sizes of the individual cavities and the crevices linking them.
Much of the water in a sample of water-saturated sediment or rock will drain from it if the sample is put in a suitable dry place. But some will remain, clinging to all solid surfaces. It is held there by the force of surface tension without which water would drain instantly from any wet surface, leaving it totally dry. The total volume of water in the saturated sample must therefore be thought of as consisting of water that can, and water that cannot, drain away.
The relative amount of these two kinds of water varies greatly from one kind of rock or sediment to another, even though their porosities may be the same. What happens depends on pore size. If the pores are large, the water in them will exist as drops too heavy for surface tension to hold, and it will drain away; but if the pores are small enough, the water in them will exist as thin films, too light to overcome the force of surface tension holding them in place; then the water will be firmly held.

GRE.READING.E06

The binary planet hypothesis—that Earth and the Moon formed simultaneously by the accretion of smaller objects—does not explain why the Moon’s iron core is so small relative to the Moon’s total volume, compared with Earth’s core relative to Earth’s total volume. According to the giant-impact hypothesis, the Moon was created during a collision between Earth and a large object about the size of Mars. Computer simulations of this impact show that both of the objects would melt in the impact and the dense core of the impactor would fall as molten rock into the liquefied iron core of Earth. The ejected matter—mantle rock that had surrounded the cores of both objects—would be almost devoid of iron. This matter would become the Moon.

According to the passage, the binary planet hypothesis holds that
 A. Earth and the Moon were formed at the same time

 B. smaller objects joined together to form Earth and the Moon

 C. the Moon’s core is the same absolute size as Earth’s core

Question 2
The giant-impact hypothesis as described in the passage answers all of the following questions EXCEPT:
 A. What happened to the rock that surrounded the impactor’s core after the impactor hit Earth?

 B. What happened to the impactor’s core after the impactor hit Earth?

 C. Where did the impactor that collided with Earth originate?

 D. Why is the Moon’s iron core small relative to that of Earth?

 E. What was the size of the impactor relative to that of Mars?

Question 3
Which of the following best describes the organization of the passage?
 A. The development of one theory into another is outlined.

 B. Two explanations are provided, both of which are revealed as inadequate.

 C. A theory is presented, and then evidence that undermines that theory is discussed.

 D. Similarities and differences between two theories are described.

 E. A flawed hypothesis is introduced, and then an alternative hypothesis is presented.

Most recent work on the history of leisure in Europe has been based on the central hypothesis of a fundamental discontinuity between preindustrial and industrial soci-eties. According to this view, the modern idea of leisure did not exist in medieval and early modern Europe: the modern distinction between the categories of work and leisure was a product of industrial capitalism. Preindustrial societies had festivals (together with informal and irregular breaks from work), while industrial societies have leisure in the form of weekends and vacations. The emergence of leisure is there-fore part of the process of modernization. If this theory is correct, there is what Michel Foucault called a conceptual rupture between the two periods, and so the very idea of a history of leisure before the Industrial Revolution is an anachronism.

To reject the idea that leisure has had a continuous history from the Middle Ages to the present is not to deny that late medieval and early modern Europeans engaged in many pursuits that are now commonly considered leisure or sporting activities— jousting, hunting, tennis, card playing, travel, and so on—or that Europe in this period was dominated by a privileged class that engaged in these pursuits. What is involved in the discontinuity hypothesis is the recognition that the people of the Middle Ages and early modern Europe did not regard as belonging to a common category activities (hunting and gambling, for example) that are usually classified together today under the heading of leisure. Consider fencing: today it may be considered a “sport,” but for the gentleman of the Renaissance it was an art or science. Conversely, activities that today may be considered serious, notably warfare, were often described as pastimes.

Serious pitfalls therefore confront historians of leisure who assume continuity and who work with the modern concepts of leisure and sport, projecting them back ontothe past without asking about the meanings contemporaries gave to their activities.

However, the discontinuity hypothesis can pose problems of its own. Historians hold-ing this view attempt to avoid anachronism by means of a simple dichotomy, cutting European history into two eras, preindustrial and industrial, setting up the binary opposition between a “festival culture” and a “leisure culture.” The dichotomy remains of use insofar as it reminds us that the rise of industrial capitalism was not purely a phenomenon of economic history, but had social and cultural preconditions and consequences. The dichotomy, however, leads to distortions when it reduces a great variety of medieval and early modern European ideas, assumptions, and practices to the simple formula implied by the phrase “festival culture.”

Question 4
The primary purpose of the passage is to
 A. refute the idea that the history of leisure is discontinuous

 B. show why one of two approaches is more useful in studying the history of leisure

 C. suggest the need for a new, more inclusive concept to replace the concept of leisure

 D. trace the development of a theory about the history of leisure

 E. point out the basis for, and the limits of, an approach to the history of leisure

Question 5
The author of the passage asserts that the “dichotomy” (line 26) can lead to which of the following?
 A. Reliance on only one of several equally valid theoretical approaches

 B. The imposition of modern conceptions and meanings on past societies

 C. Failure to take into account the complexity of certain features of European culture

 D. Failure to utilize new conceptual categories in the study of the history of leisure

 E. Failure to take account of the distinction between preindustrial and industrial societies

Question 6
According to the passage, the “simple dichotomy” (line 26) is useful primarily because it serves as
 A. a way of calling historians’ attention to certain facts about the Industrial Revolution

 B. an antidote to the oversimplification encouraged by such terms as “festival culture”

 C. a device for distinguishing between the work and the leisure activities of preindustrial Europeans

 D. a way of understanding the privileged class of medieval Europe by viewing its activities in modern terms

 E. a tool for separating social history, including the history of leisure, from economic history

Question 7
Which of the following best describes the organization of the passage as a whole?
 A. Two hypotheses are discussed, and evidence in support of one is presented.

 B. A hypothesis is presented and discussed, and a limitation to the hypothesis is identified.

 C. A hypothesis is proposed, its supposed advantages are shown to be real, and its supposed disadvantages are shown to be illusory.

 D. A problem is identified, two hypotheses are advanced to resolve it, and both are rejected.

 E. A problem is identified, two resolutions are proposed, and a solution combining elements of both is recommended.

James W. Coleman’s book on John Edgar Wideman’s literary career addresses the needs of a general, if well-read, public rather than the esoteric vanities of scholarly special-ists, whom he neither ignores nor flatters. To assume the former audience was familiar with every work Wideman ever penned would have been pretentious. Instead, Cole- man furnishes more than ample descriptive criticism and background information, avoiding the cryptic allusiveness that is favored by some academic critics but that dis-courages the undergraduate audience he likely envisioned. Unfortunately, this accent on bringing serious Wideman criticism to a broader audience often frustrates the reader who wishes that announced themes, techniques, and stylistic devices would not whisk by as quickly as world capitals on a seven-day package tour of the globe.

Question 8
The reference to “a seven-day package tour of the globe” (line 10) is most likely meant to suggest a treatment that is
 A. inclusive

 B. cursory

 C. focused

 D. broad based

 E. substantial

The painter Peter Brandon never dated his works, and their chronology is only now beginning to take shape in the critical literature. A recent dating of a Brandon self-portrait to 1930 is surely wrong. Brandon was 63 years old in 1930, yet the painting shows a young, dark-haired man—obviously Brandon, but clearly not a man of 63.

Question 9
Which of the following, if justifiably assumed, allows the conclusion to be properly drawn?
 A. There is no securely dated self-portrait of Brandon that he painted when he was significantly younger than 63.

 B. In refraining from dating his works, Brandon intended to steer critical discussion of them away from considerations of chronology.

 C. Until recently, there was very little critical literature on the works of Brandon.

 D. Brandon at age 63 would not have portrayed himself in a painting as he had looked when he was a young man.

 E. Brandon painted several self-portraits that showed him as a man past the age of 60.

Experts have differed about where the genus Varanus (monitor lizards) originated. Because most existing species live in Australia, early researchers concluded that Varanus originated in Australia and subsequently island hopped westward along the Indo-Australian archipelago. Herpetologist Robert Mertens later argued that Varanus probably originated in the archipelago. Chromosomal analysis has since supported Mertens’ contention, and in addition, geologic evidence points to a collision between the archipelago and the Australian landmass after Varanus evolved—a fact that could account for the genus’ present distribution.

Question 10
It can be inferred from the passage that the geographical distribution of the Komodo dragon is
 A. currently less restricted than it was at the time researchers first began investigating the origins of the genus Varanus

 B. currently more restricted than it was at the time researchers first began investigating the origins of the genus Varanus

 C. less restricted than is the distribution of the genus Varanus as a whole

 D. more restricted than is the distribution of the genus Varanus as a whole

 E. viewed as evidence in favor of the hypothesis that the genus Varanus originated in the Indo-Australian archipelago

Question 11
Which of the following elements in the debate over the origin of Varanus is NOT provided in the passage?
 A. The evidence that led Mertens to argue that Varanus originated in the Indo-Australian archipelago

 B. The evidence that led early researchers to argue that Varanus originated in Australia

 C. A possible explanation of how Varanus might have spread to the Indo-Australian archipelago if it had originated in Australia

 D. A possible explanation of how Varanus might have spread to Australia if it had originated in the Indo-Australian archipelago

 E. An indication of the general present-day distribution of Varanus species between Australia and the Indo-Australian archipelago

Question 12
It can be inferred that which of the following is true of the “geologic evidence” (line 6)?
 A. It was first noted by Mertens as evidence in favor of his theory about the origins of Varanus.

 B. It cannot rule out either one of the theories about the origins of Varanus discussed in the passage.

 C. It accounts for the present distribution of the Komodo dragon.

 D. It has led to renewed interest in the debate over the origins of Varanus.

 E. It confirms the conclusions reached by early researchers concerning the origins of Varanus.

Geographers and historians have traditionally held the view that Antarctica was first sighted around 1820, but some sixteenth-century European maps show a body that resembles the polar landmass, even though explorers of the period never saw it. Some scholars, therefore, argue that the continent must have been discovered and mapped by the ancients, whose maps are known to have served as models for the European cartographers.

Question 13
Which of the following, if true, is most damaging to the inference drawn by the scholars?
 A. The question of who first sighted Antarctica in modern times is still much debated, and no one has been able to present conclusive evidence.

 B. Between 3,000 and 9,000 years ago, the world was warmer than it is now, and the polar landmass was presumably smaller.

 C. There are only a few sixteenth-century global maps that show a continental landmass at the South Pole.

 D. Most attributions of surprising accomplishments to ancient civilizations or even extraterrestrials are eventually discredited or rejected as preposterous.

 E. Ancient philosophers believed that there had to be a large landmass at the South Pole to balance the northern continents and make the world symmetrical.

GRE.WEIXUE.READING.01.The molecules of carbon dioxide

The molecules of carbon dioxideThe molecules of carbon dioxide in the Earth’s atmosphere affect the heat balance of the Earth by acting as a one-way screen. Although these molecules allow radiation at visible wavelengths, where most of the energy of sunlight is concentrated, to pass through, they absorb some of the longer-wavelength, infrared emissions radiated from the Earth’s surface, radiation that would otherwise be transmitted back into space. For the Earth to maintain a constant average temperature, such emissions from the planet must balance incoming solar radiation. If there were no carbon dioxide in the atmosphere, heat would escape from the Earth much more easily. The surface temperature would be so much lower that the oceans might be a solid mass (solid mass: 实体) of ice.

Today, however, the potential problem is too much carbon dioxide. The burning of fossil fuels and the clearing of forests have increased atmospheric carbon dioxide by about 15 percent in the last hundred years, and we continue to add carbon dioxide to the atmosphere. Could the increase in carbon dioxide cause a global rise in average temperature, and could such a rise have serious consequences for human society? Mathematical models that allow us to calculate the rise in temperature as a function of the increase indicate that the answer is probably yes.

Under present conditions a temperature of-18℃ can be observed at an altitude of 5 to 6 kilometers above the Earth. Below this altitude (called the radiating level), the temperature increases by about 6℃ per kilometer approaching the Earth’s surface, where the average temperature is about 15℃. An increase in the amount of carbon dioxide means that there are more molecules of carbon dioxide to absorb infrared radiation. As the capacity of the atmosphere to absorb infrared radiation increases, the radiating level and the temperature of the surface must rise.

​One mathematical model predicts that doubling the atmospheric carbon dioxide would raise the global mean surface temperature by 2.5℃. This model assumes that the atmosphere’s relative humidity (relative humidity: n.相对湿度) remains constant and the temperature decreases with altitude at a rate of 6.5℃ per kilometer. The assumption of constant relative humidity is important, because water vapor in the atmosphere is another efficient absorber of radiation at infrared wavelengths. Because warm air can hold more moisture than cool air, the relative humidity will be constant only if the amount of water vapor in the atmosphere increases as the temperature rises. Therefore, more infrared radiation would be absorbed and reradiated back to the Earth’s surface. The resultant warming at the surface could be expected to melt snow and ice, reducing the Earth’s reflectivity. More solar radiation would then be absorbed, leading to a further increase in temperature.

TOEFL.READING.E42.Geographic Isolation Of Species

Geographic Isolation Of Species
Biologist Ernst Mayr defined a species as “an actually or potentially interbreeding population that does not interbreed with other such populations when there is opportunity to do so.” A key event in the origin of many species is the separation of a population with its gene pool (all of the genes in a population at any one time) from other populations of the same species, thereby preventing population interbreeding. With its gene pool isolated, a separate population can follow its own evolutionary course. In the formation of many species, the initial isolation of a population seems to have been a geographic barrier. This mode of evolving new species is called allopatric speciation.

1.The word “key” in the passage is closest in meaning to
A. early

B. crucial

C. noticeable

D. frequent

2.The word “initial” in the passage is closest in meaning to
A. best

B. usual

C. first

D. actual

3.According to paragraph 1, allopatric speciation is possible when
A. a population contains all the different genes present in a species at a particular time

B. a population becomes isolated due to the presence of a geographic barrier

C. genetic mixing begins to occur in previously separate populations of a species

D. a species is successful in crossing a geographic barrier


Many factors can isolate a population geographically. A mountain range may emerge and gradually split a population of organisms that can inhabit only lowland lakes, certain fish populations might become isolated in this way. Similarly, a creeping glacier may gradually divide a population, or a land bridge such as the Isthmus of Panama may form and separate the marine life in the ocean waters on either side.

4.How is paragraph 2 related to paragraph 1?
A. Paragraph 2 points out a number of ways in which the phenomenon of geographic isolation mentioned in paragraph 1 can occur

B. Paragraph 2 identifies discoveries that led to the conclusion presented in paragraph 1 that geographic isolation has played a role in the origin of many species

C. Paragraph 2 provides evidence supporting the statement in paragraph 1 that a population can follow its own evolutionary course once its gene pool becomes isolated

D. Paragraph 2 explains why the term “allopatric” was adopted to describe the method of speciation described in paragraph 1

How formidable must a geographic barrier be to keep populations apart? It depends on the ability of the organisms to move across barriers. Birds and coyotes can easily cross mountains and rivers. The passage of wind-blown tree pollen is also not hindered by such barriers, and the seeds of many plants may be carried back and forth on animals. In contrast, small rodents may find a deep canyon or a wide river an effective barrier. For example, the Grand Canyon, in the southwestern United States, separate the range of the white-tailed antelope squirrel from that of the closely related Harris’ antelope squirrel. Smaller, with a shorter tail that is white underneath, the white-tailed antelope squirrel inhabits deserts north of the canyon and west of the Colorado River in southern California. Harris' antelope squirrel has a more limited range in deserts south of the Grand Canyon.

5.In paragraph 3, the author contrasts a variety of organisms to illustrate which of the following points?
A. Geographic barriers are less likely to keep apart populations of plants than populations of animals.

B. Geographic barriers are more likely to keep apart populations of large organisms than populations of small organisms

C. Some members of a species are able to cross geographic barriers, while other members of the same species are not.

D. The effectiveness of geographic barriers in keeping organisms apart depends on an organism’s ability to move across barriers.

6.Paragraph 3 supports the idea that white-tailed antelope squirrels and Harris' antelope squirrels have which of the following in common?
A. They are the two smallest rodents now found in the southwestern United States.

B. They have white coloring underneath their tails

C. They cannot cross the Grand Canyon

D. They cannot survive in desert conditions

Geographic isolation creates opportunities for new species to develop, but it does not necessarily lead to new species because speciation occurs only when the gene pool undergoes enough changes to establish reproductive barriers between the isolated population and its parent population. The likelihood of allopatric speciation increases when a population is small as well as isolated, making it more likely than a large population to have its gene pool changed substantially. For example, in less than two million years, small populations of stray animals and plants from the South American mainland that managed to colonize the Galapagos Islands gave rise to all the species that now inhabit the islands.

7.The word “undergoes” in the passage is closest in meaning to
A. experiences

B. allows

C. prevents

D. causes

8.Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information
上面这一段的第一句话
A. Geographic isolation is sometimes but not always the reason for the creation of reproductive barriers between a parent population and the populations descended from it

B. Genetic changes in a geographical isolated population do not necessarily make the population look different enough from its parent population to be considered a new species

C. Geographical isolation allows the separated populations to evolve independently of each other and so can lead to the formation of new species

D. Geographic isolation can lead to new species only if the gene pool of the isolated population changes enough to prevent it from reproducing with the parent population

9.According to paragraph 4, why does the size of a population affect the likelihood of allopatric speciation?
A. Because smaller populations are more likely than larger ones to become geographically isolated

B. Because the gene pool of a small isolated population is more likely to undergo substantial change than is the gene pool of a larger population

C. Because a small isolated population can become a new species with substantially less change to its gene pool than would be required by a larger population

D. Because smaller populations are more likely to be made up of stray animals or plants than larger populations are

10.The word “managed” in the passage is closest in meaning to
A. were able

B. were forced

C. arrived

D. expanded

When oceanic islands are far enough apart to permit populations to evolve in isolation, but close enough to allow occasional dispersions to occur, they are effectively outdoor laboratories of evolution. The Galapagos island chain is one of the world's greatest showcases of evolution . Each island was born from underwater volcanoes and was gradually covered by organisms derived from strays that rode the ocean currents and winds from other islands and continents. Organisms can also be carried to islands by other organisms, such as sea birds that travel long distances with seeds clinging to their feathers.

11.Paragraph 5 supports the idea that the Galapagos island chain was able to become "one of the world's greatest showcases of evolution" primarily because of
A. the richness of the volcanic soil of each of the islands in the chain

B. the distance of the individual islands from each other and from the mainland

C. the relativity long time it took for the islands to become covered by organisms

D. the outdoor laboratories that scientists have built on the islands to study evolution

The species on the Galapagos Islands today, most of which occur nowhere else, descended from organisms that floated, flew, or were blown over the sea from the South American mainland. For instance, the Galapagos island chain has a total of thirteen species of closely related birds called Galapagos finches. These birds have many similarities but differ in their feeding habits and their beak type, which is correlated with what they eat. Accumulated evidence indicates that all thirteen finch species evolved from a single small population of ancestral birds that colonized one of the islands. Completely isolated on the island after migrating from the mainland, the founder population may have undergone significant changes in its gene pool and become a new species. Later, a few individuals of this new species may have been blown by storms to a neighboring island. Isolated on this second island, the second founder population could have evolved into a second new species, which could later recolonize the island from which its founding population emigrated. Today each Galapagos island has multiple species of finches, with as many as ten on some islands.


12.According to paragraph 6, what is true about the thirteen species of Galapagos finches?
A. All thirteen species are now found on most of the Galapagos Islands

B. All thirteen species are descended from the same population of ancestral birds

C. All thirteen species evolved on the island that was originally colonized by finches from the mainland.

D. All thirteen species occur only in small, completely isolated populations.

13.Look at the four squares [■] that indicate where the following sentence could be added to the passage. Where would the sentence best fit? Click on a square [■] to add the sentence to the passage.
最后一段的某个位置

This process of speciation and colonization could have been repeated over and over again, gradually involving all the islands in the chain..

14.An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. The geographic isolation of a population can result in the rise of a new species.
A.Isolation can result when a geographic barrier forms and splits a population or when a few organisms somehow get carried across an existing geographic barrier and form a new population

B.Speciation is more likely when an isolated population is small because significant genetic changes are more likely to occur in a small population than in a large one

C.Because of the geographic isolation of the Galapagos Islands, the species that now inhabit them have gene pools that have not changed very much since the islands were first populated.

D.Fish populations are more easily isolated by geographic barriers than are populations of most other organisms because fish cannot move across areas where there is no water.

E.The Galapagos Islands are well situated for speciation because they provide opportunities for population isolation while also making occasional dispersions between islands possible.

F.Evidence indicates that the first organisms to reach the Galapagos Islands were probably a small population of finches that, in less than two million years of isolation, evolved into thirteen species.

TOEFL.READING.E44.Seagrasses

Many areas of the shallow sea bottom are covered with a lush growth of aquatic flowering plants adapted to live submerged in seawater. These plants are collectively called seagrasses. Seagrass beds are strongly influenced by several physical factors. The most significant is water motion: currents and waves. Since seagrass systems exist in both sheltered and relatively open areas, they are subject to differing amounts of water motion. For any given seagrass system, however, the water motion is relatively constant. Seagrass meadows in relatively turbulent waters tend to form a mosaic of individual mounds, whereas meadows in relatively calm waters tend to form flat, extensive carpets. The seagrass beds, in turn, dampen wave action, particularly if the blades reach the water surface. This damping effect can be significant to the point where just one meter into a seagrass bed the wave motion can be reduced to zero. Currents are also slowed as they move into the bed.
1.According to paragraph 1, which of the following is true about seagrasses in calm ocean waters?
A. They will not survive for very long without the nutrients brought In by fast-moving waters.
B. They tend to form beds covering large areas along the ocean floor.
C. They usually are arranged in separate mounds.
D. They grow more slowly than do seagrasses in fast-moving waters.
2.According to paragraph 1, which of the following is MOST likely to describe a bed in which seagrasses reach the surface of the water?
A. The water is almost completely still.
B. The bed often has major damage from strong waves or currents.
C. The bed is generally no more than one square meter in size.
D. Grasses form a mosaic of individual mounds.

The slowing of wave action and currents means that seagrass beds tend to accumulate sediment. However, this is not universal and depends on the currents under which the bed exists. Seagrass beds under the influence of strong currents tend to have many of the lighter particles, including seagrass debris, moved out, whereas beds in weak current areas accumulate lighter detrital material. It is interesting that temperate seagrass beds accumulate sediments from sources outside the beds, whereas tropical seagrass beds derive most of their sediments from within.
3.Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.
A. Light particles and debris collect in some seagrass beds, but are washed out of those affected by strong currents.
B. Seagrass beds under the influence of strong currents tend to accumulate many of the lighter particles from other beds.
C. The strength of the currents determines how quickly accumulated seagrass debris is moved out of the beds.
D. Seagrass debris and other light particles are often moved from areas of strong currents to areas of weak currents.
4.The word "derive" in the passage is closest in meaning to
A. maintain
B. expel
C. obtain
D. enrich


Since most seagrass systems are depositional environments, they eventually accumulate organic material that leads to the creation of fine-grained sediments with a much higher organic content than that of the surrounding unvegetated areas. This accumulation, in turn, reduces the water movement and the oxygen supply. The high rate of metabolism (the processing of energy for survival) of the microorganisms in the sediments causes sediments to be anaerobic (without oxygen) below the first few millimeters. According to ecologist J. W. Kenworthy, anaerobic processes of the microorganisms in the sediment are an important mechanism for regenerating and recycling nutrients and carbon, ensuring the high rates of productivity—that is, the amount of organic material produced-that are measured in those beds. In contrast to other productivity in the ocean, which is confined to various species of algae and bacteria dependent on nutrient concentrations in the water column, seagrasses are rooted plants that absorb nutrients from the sediment or substrate. They are, therefore, capable of recycling nutrients into the ecosystem that would otherwise be trapped in the bottom and rendered unavailable.
5.According to paragraph 3, which of the following does NOT accurately describe the sediments that collect in seagrass beds?
A. Fine-grained
B. Only a few millimeters deep
C. Low in oxygen
D. Rich in organic matter
6.The word "confined" in the passage is closest in meaning to
A. related
B. limited
C. relevant
D. helpful
7.According to paragraph 3, how do seagrasses affect the nutrient supply in the ecosystem?
A. Because of their high rate of metabolism, they consume a large percentage of the available nutrients.
B. They attract various species of algae and bacteria that produce high nutrient concentrations in the water column.
C. They take up carbon and other nutrients trapped on the sea bottom and bring them back into use.
D. Through anaerobic processes at their roots, they produce a very nutrient-rich sediment.

Other physical factors that have an effect on seagrass beds include light, temperature, and desiccation (drying out). For example, water depth and turbidity (density of particles in the water) together or separately control the amount of light available to the plants and the depth to which the seagrasses may extend. Although marine botanist W. A. Setchell suggested early on that temperature was critical to the growth and reproduction of eelgrass, it has since been shown that this particularly widespread seagrass grows and reproduces at temperatures between 2 and 4 degrees Celsius in the Arctic and at temperatures up to 28 degrees Celsius on the northeastern coast of the United States. Still, extreme temperatures, in combination with other factors, may have dramatic detrimental effects. For example, in areas of the cold North Atlantic, ice may form in winter. Researchers Robertson and Mann note that when the ice begins to break up, the wind and tides may move the ice around, scouring the bottom and uprooting the eelgrass. In contrast, at the southern end of the eelgrass range, on the southeastern coast of the United States, temperatures over 30 degrees Celsius in summer cause excessive mortality. Seagrass beds also decline if they are subjected to too much exposure to the air. The effect of desiccation is often difficult to separate from the effect of temperature. Most seagrass beds seem tolerant of considerable changes in salinity (salt levels) and can be found in brackish (somewhat salty) waters as well as in full- strength seawater.
8.It can be inferred from paragraph 4 that the reason seagrasses do not grow in very deep water is that
A. they cannot handle intense water pressure
B. deep water is too cold
C. they would not get enough light
D. deep water is too salty
9.In paragraph 4, why does the author mention that eelgrass thrives in both the Arctic and in the northeastern United States?
A. To show that environments with extreme temperatures rarely have any effect on eelgrass
B. To identify the northern and southern limits of the range where eelgrass is found
C. To support the author's statement that eelgrass is a particularly widespread kind of seagrass
D. To cite evidence tending to disprove one view about the importance of temperature to the growth of eelgrass
10.The word "detrimental" in the passage is closest in meaning to
A. harmful
B. significant
C. unexpected
D. distinct
11.Paragraph 4 suggests that which of the following would be the LEAST likely to cause major damage to eelgrass and other common seagrasses?
A. Factors related to extreme temperatures
B. Exposure to air
C. Major changes in salinity
D. The movement of ice on the seafloor
12.The phrase "tolerant of" in the passage is closest in meaning to
A. unused to
B. strongly affected by
C. protected from
D. able to withstand
13.Look at the four squares [■] that indicate where the following sentence could be added to the passage. Where would the sentence best fit? Click on a square [■] to add the sentence to the passage
第一段
Seagrasses grow together in dense patches, or beds, with as many as 4,000 blades per square meter..
14.Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points. Drag your answer choices to the spaces where they belong. To remove an answer choice, click on it. Seagrasses are aquatic flowering plants that grow in either sheltered or open areas of the sea
A.Seagrass beds are influenced by several physical factors, the most significant being the stability of the sea bottom, which must anchor them against the currents.
B.Because they slow currents and waves, seagrass beds collect deposits of rich organic sediments, which are home to many anaerobic microorganisms.
C.Unlike sea organisms that depend on the water column for their productivity, seagrasses ensure high rates of productivity by taking nutrients from ocean floor sediment.
D.Sediments in seagrass beds vary by region, with temperate beds accumulating sediments from within, and tropical beds collecting sediments from without.
E.Seagrasses under weak currents tend to have higher rates of metabolism than those under strong currents, perhaps because of differences in oxygen levels.
F.Although seagrasses survive in temperatures ranging from 2 to 28 degrees Celsius, more extreme temperatures can damage them, as can desiccation and lack of light.

TOEFL.READING.E44.The Use Of The Camera Obscura

The Use Of The Camera Obscura
The precursor of the modern camera, the camera obscura is a darkened enclosure into which light is admitted through a lens in a small hole. The image of the illuminated area outside the enclosure is thrown upside down as if by magic onto a surface in the darkened enclosure. This technique was known as long ago as the fifth century B.C. in China. Aristotle also experimented with it in the fourth century B.C., and Leonardo da Vinci described it in his notebooks in 1490. In 1558 Giovanni Battista Della Porta wrote in his twenty-volume work Magia naturalis (meaning "natural magic") instructions for adding a convex lens to improve the quality of the image thrown against a canvas or panel in the darkened area where its outlines could be traced. Later, portable camera obscuras were developed, with interior mirrors and drawing tables on which the artist could trace the image. For the artist, this technique allows forms and linear perspective to be drawn precisely as they would be seen from a single viewpoint. Mirrors were also used to reverse the projected images to their original positions.
1.What can be inferred from paragraph 1 about Giovanni Battista Della Porta's contribution to the camera obscura?
A. He translated a Chinese description of the use of the camera obscura and made the technique available to artists.
B. His convex lens made the projected image easier to trace.
C. His version of the camera obscura allowed for the later addition of a mirror.
D. His improvements relied heavily on design changes proposed earlier by Leonardo da Vinci.
2.The word “portable” in the passage is closest in meaning to
A. valuable
B. practical
C. moveable
D. popular
3.The word "projected" in the passage is closest in meaning to
A. whole
B. corrected
C. enlarged
D. shown
Did some of the great masters of painting, then, trace their images using a camera obscura? Some art historians are now looking for clues of artists' use of such devices. One of the artists whose paintings are being analyzed from this point of view is the great Dutch master, Jan Vermeer, who lived from 1632 to 1675 during the flowering of art and science in the Netherlands, including the science of optics. Vermeer produced only about 30 known paintings, including his famous The Art of Painting. The room shown in it closely resembles the room in other Vermeer paintings, with lighting coming from a window on the left, the same roof beams, and similar floor tiles, suggesting that the room was fitted with a camera obscura on the side in the foreground. The map hung on the opposite wall was a real map in Vermeer's possession, reproduced in such faithful detail that some kind of tracery is suspected. When one of Vermeer’s paintings was X-rayed, it did not have any preliminary sketches on the canvas beneath the paint, but rather the complete image drawn in black and white without any trial sketches. Vermeer did not have any students, did not keep any records, and did not encourage anyone to visit his studio, facts that can be interpreted as protecting his secret use of a camera obscura.
4.Paragraph 2 answers which of the following questions about paintings by Vermeer?
A. What characteristics of Vermeer’s paintings suggest that he may have used a camera obscura?
B. Why did Vermeer produce only about 30 paintings?
C. Do Vermeer's paintings in general suggest that he was unable to paint accurately without using a camera obscura?
D. Why did Vermeer need to draw an image on the canvas of the painting that was X-rayed if he was using a camera obscura?
5.Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.
第二段，第三句話
A. One artist with a particularly interesting point of view about the use of the camera obscura in painting was Jan Vermeer, who lived in the Netherlands from 1632 to 1675.
B. Historical analyses suggest that Dutch masters were interested in the science of optics, so they may have used the camera obscura to trace images.
C. The use of the camera obscura is being analyzed in the paintings of Jan Vermeer, who lived in the Netherlands when art and science were flourishing there.
D. One view held by historians is that most Dutch masters were as interested in art as they were in science, and that provides clues about the techniques used in their paintings.
6.What does paragraph 2 indicate about Vermeer’s The Art of Painting?
A. It is the first in a series of about 30 paintings that he created.
B. It may have been painted by one of his students.
C. it was in his possession until his death in 1675.
D. It has the same setting as several other works of his.
7.The word "faithful" in the passage is closest in meaning to
A. unusual
B. extensive
C. exact
D. historical
8.Why does the author provide the information that "When one of Vermeer's paintings was X-rayed, it did not have any preliminary sketches on the canvas beneath the paint, but rather the complete image drawn in black and white without any trial sketches"?
A. To provide an example of a way to learn about the practices of artists who did not keep good records
B. To emphasize Vermeer’s confidence and skill as an artist
C. To provide evidence that Vermeer may have traced the image using a camera obscura
D. To argue that Vermeer did his preliminary sketching on paper, rather than on canvas
In recent times the British artist David Hockney has published his investigations into the secret use of the camera obscura, claiming that for up to 400 years, many of Western art’s great masters probably used the device to produce almost photographically realistic details in their paintings. He includes in this group Caravaggio, Hans Holbein, Leonardo da Vinci, Diego Velazquez, Jean-Auguste-Dominique Ingres, Agnolo Bronzino, and Jan van Eyck. From an artist’s point of view, Hockney observed that a camera obscura compresses the complicated forms of a three-dimensional scene into two-dimensional shapes that can easily be traced and also increases the contrast between light and dark, leading to the chiaroscuro effect seen in many of these paintings. In Jan van Eyck’s The Marriage of Giovanni Arnolfini and Giovanna Cenami, the complicated foreshortening in the chandelier and the intricate detail in the bride’s garments are among the clues that Hockney thinks point to the use of the camera obscura.
9.According to paragraph 3, Hockney believes that all of the following indicate use of a camera obscura EXCEPT
A. very detailed, realistic work
B. increased contrast between light and dark
C. oversimplification of forms when the image is traced
D. complicated foreshortening of objects
10.The word "intricate” in the passage is closest in meaning to
A. surprising
B. complex
C. beautiful
D. clear
So what are we to conclude? If these artists did use a camera obscura, does that diminish their stature? Hockney argues that the camera obscura does not replace artistic skill in drawing and painting. In experimenting with it, he found that it is actually quite difficult to use for drawing, and he speculates that the artists probably combined their observations from life with tracing of shapes.
11.The word “diminish" in the passage is closest in meaning to
A. reduce
B. affect
C. reflect
D. determine
12.According to paragraph 4, what does Hockney argue about the use of the camera obscura in producing art?
A. Works produced using a camera obscura do not deserve as much respect as those produced without it.
B. The camera obscura was probably used primarily as a training device, rather than used in producing finished works.
C. Use of the camera obscura by Western art’s great masters was probably relatively rare.
D. While the use of the camera obscura may have helped artists, they still needed to have significant artistic ability.
13.Look at the four squares [■] that indicate where the following sentence could be added to the passage. Where would the sentence best fit? Click on a square [■] to add the sentence to the passage
第一段
All these developments helped artists to create accurate images of objects, people, and scenes..
14.Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points. Drag your answer choices to the spaces where they belong. To remove an answer choice, click on it. The camera obscura is a darkened enclosure into which light is admitted through a lens in a small hole
A.Evidence that the use of the camera obscura has long been known is provided by its description in many sources, including works dating back to Chinese writers from the fifth century B.C.
B.Some historians who have studied paintings by Western masters have found clues indicating that the masters may have secretly used the camera obscura in their works.
C.It is now widely believed that the use of the camera obscura led to the development of a style of photographic realism in Western art.
D.The camera obscura was most widely used by artists in Seventeenth-century Netherlands, a period when art and science thrived
E.The unique features of Vermeer’s The Art of Painting make it unlikely that it was made with a camera obscura, as opposed to his other works.
F.The artist David Hockney has speculated that artists probably combined the use of the camera A with their own original observations from life.

TOEFL.READING.E44.From Fish to Terrestrial Vertebrates

From Fish to Terrestrial Vertebrates
One of the most significant evolutionary events that occurred on Earth was the transition of water-dwelling fish to terrestrial tetrapods (four-limbed organisms with backbones). Fish probably originated in the oceans, and our first records of them are in marine rocks. However, by the Devonian Period (408 million to 362 million years ago), they had radiated into almost all available aquatic habitats, including freshwater settings. One of the groups whose fossils are especially common in rocks deposited in fresh water is the lobe-finned fish.

1.Paragraph 1 supports which of the following statements about fish evolution?
A. Lobe-finned fish were among the earliest types of fish to appear.

B. Fish began living in freshwater habitats only after originating elsewhere.

C. Lobe-finned fish radiated into almost all available aquatic habitats.

D. During the Devonian, lobe-finned fish were more common in marine than in freshwater habitats.

The freshwater Devonian lobe-finned fish rhipidistian crossopterygian is of particular interest to biologists studying tetrapod evolution. These fish lived in river channels and lakes on large deltas. The delta rocks in which these fossils are found are commonly red due to oxidized iron minerals, indicating that the deltas formed in a climate that had alternate wet and dry periods. If there were periods of drought, any adaptations allowing the fish to survive the dry conditions would have been advantageous. In these rhipidistians，several such adaptations existed. It is known that they had lungs as well as gills for breathing. Cross sections cut through some of the fossils reveal that the mud filling the interior of the carcass differed in consistency and texture depending on its location inside the fish. These differences suggest a saclike cavity below the front end of the gut that can only be interpreted as a lung. Gills were undoubtedly the main source of oxygen for these fish, but the lungs served as an auxiliary breathing device for gulping air when the water became oxygen depleted, such as during extended periods of drought. So, these fish had already evolved one of the prime requisites for living on land: the ability to use air as a source of oxygen.

2.According to paragraph 2, what do the minerals in the delta rocks containing rhipidistian crossopterygian fossils reveal?
A. These deltas formed in dry periods but gradually became wetter.

B. These deltas contain different types of iron minerals than do the surrounding areas.

C. Most rhipidistian crossopterygian fish died when the climate became dry.

D. Rhipidistian crossopterygian fish lived in areas that experienced alternate dry and wet periods.

3.The word "advantageous" in the passage is closest in meaning to
A. beneficial

B. necessary

C. remarkable

D. common

4.In paragraph 2, why does the author include the information that mud inside rhipidistian crossopterygian fossils differed in consistency and texture depending on where the mud was located?
A. To provide evidence that rhipidistian crossopterygian lived in river channels and lakes on large deltas.

B. To identify an effect of the oxidation of iron minerals on the evolution of rhipidistian crossopterygian.

C. To help explain why scientists have concluded that rhipidistian crossopterygian probably had lungs.

D. To explain why scientists decided to cut cross sections through some fossils of rhipidistian crossopterygian.

5.Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.
倒数第二句
A. Because the lungs of these fish were able to provide only a small amount of oxygen, these fish obtained most of their oxygen through their gills during periods of drought.

B. During periods of extended drought, these fish used their lungs to increase their intake of oxygen beyond the levels absorbed by the gills in normal times.

C. Although these fish primarily used their gills to obtain oxygen, they used their lungs to obtain oxygen from the air when there was not enough in the water.

D. During periods of extended drought, the gills became an auxiliary breathing device and the lungs became the main source of oxygen for these fish.

A second adaptation of these fish was in the structure of the lobe fins. The fins were thick, fleshy, and quite sturdy, with a median axis of bone down the center. They could have been used as feeble locomotor devices on land, perhaps good enough to allow a fish to flop its way from one pool of water that was almost dry to an adjacent pond that had enough water and oxygen for survival. These fins eventually changed into short, stubby legs. The bones of the fins of a Devonian rhipidistian exactly match in number and position the limb bones of the earliest known tetrapods, the amphibians. It should be emphasized that the evolution of lungs and limbs was in no sense an anticipation of future life on land. These adaptations developed because they helped fish to survive in their existing aquatic environment.

6.According to paragraph 3, the structure of the fins of rhipidistian crossopterygian may have allowed these fish to
A. reduce the amount of oxygen needed for survival

B. develop thick, sturdy bones

C. move more efficiently in water

D. move short distances over areas that were mostly dry

7.The word "adjacent" in the passage is closest in meaning to:
A. nearby

B. available

C. temporary

D. fresh

What ecological pressures might have caused fishes to gradually abandon their watery habitat and become increasingly land-dwelling creatures? Changes in climate during the Devonian may have had something to do with this if freshwater areas became progressively more restricted. Another impetus may have been new sources of food. The edges of ponds and streams surely had scattered dead fish and other water-dwelling. In addition, plants had emerged into terrestrial habitats in areas near streams and ponds, and crabs and other arthropods were also members of this earliest terrestrial community. Thus, by the Devonian the land habitat marginal to freshwater was probably a rich source of protein that could be exploited by an animal that could easily climb out of water. Evidence from teeth suggests that these earliest tetrapods did not utilize land plants as food; they were presumably carnivorous and had not developed the ability to feed on plants.

8.The word “progressively” in the passage is closest in meaning to
A. increasingly

B. noticeably

C. occasionally

D. rapidly

9.In paragraph 4, why does the author point out that crabs and other arthropods were already living on land when the ancestors of the first tetrapods began living there?
A. To account for the presence of dead fish along the edges of ponds and streams during the Devonian.

B. To support the claim that climate change caused freshwater habitats to become more restricted during the Devonian.

C. To identify a consequence of the emergence of plants into terrestrial habitats near ponds and streams.

D. To identify a possible reason for why certain fish gradually became terrestrial organisms.

10.According to paragraph 4, teeth of the earliest tetrapods suggest that these tetrapods
A. competed with other animals for protein

B. were probably carnivores

C. could easily climb out of water

D. were able to eat plants

How did the first tetrapods make the transition to a terrestrial habitat? Like early land plants such as rhyniophytes, they made only a partial transition; they were still quite tied to water. However, many problems that faced early land plants were not applicable to the first tetrapods.The ancestors of these animals already had a circulation system, and they were mobile, so that they could move to water to drink. Furthermore, they already had lungs, which rhipidistians presumably used for auxiliary breathing. The principal changes for the earliest tetrapods were in the skeletal system—changes in the bones of the fins, the vertebral column, pelvic girdle, and pectoral girdle.

11.According to paragraph 5, which of the following was true of the first tetrapods?
A. They became dependent for food on organisms already living on land.

B. They needed to develop new mechanisms for obtaining nutrients.

C. They continued to live in close association with aquatic environments.

D. They were evolutionarily far removed from their rhipidistian ancestors.

12.According to paragraph 5, what was the main way that the earliest tetrapods differed from their immediate fish ancestors?
A. The tetrapods had a different skeletal structure.

B. The tetrapods had more sources of food available.

C. The tetrapods had a circulation system.

D. The tetrapods could move to new pools of water.

13.Look at the four squares [■] that indicate where the following sentence could be added to the passage. Where would the sentence best fit? Click on a square [■] to add the sentence to the passage.

倒数第二段某个位置

These would have been deposited by the receding waters of droughts, during which many aquatic animals must have died..

14.Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points. Drag your answer choices to the spaces where they belong. To remove an answer choice, click on it. Freshwater lobe-finned fish may be the direct ancestors of terrestrial tetrapods.
A.Rhipidistian crossopterygian had features such as primitive lungs and thick fins that could have helped it survive dry periods.

B.During the Devonian, the number of bones increased in the fins of rhipidistians, improving such animals’ ability to swim and move over land.

C.Shortly after the earliest tetrapods developed lungs, plants and other animals began to flourish on land.

D.By the Devonian period, lobe-finned fish preferred freshwater habitats to life in the ocean.

E.A drier climate and new sources of food on land may have encouraged the lobe-finned fish’s move to a terrestrial existence.

F.Early tetrapods remained closely connected to water, but several of their body structures were adapted for life on land.

TOEFL.READING.E45.Feeding Strategies In The Ocean

Feeding Strategies In The Ocean
In the open sea, animals can often find food reliably available in particular regions or seasons (e g., in coastal areas in springtime). In these circumstances, animals are neither constrained to get the last calorie out of their diet nor is energy conservation a high priority. In contrast, the food levels in the deeper layers of the ocean are greatly reduced, and the energy constraints on the animals are much more severe . To survive at those levels, animals must maximize their energy input, finding and eating whatever potential food source may be present.
1.The word "severe" in the passage is closest in meaning to
A. extreme
B. complex
C. basic
D. immediate
2.What can be inferred from paragraph 1 about why energy conservation is not a high priority for ocean animals in coastal waters during the spring?
A. Those animals are least active during the spring
B. Those animals have a plentiful supply of food
C. Those animals have to expend energy to avoid predators.
D. Those animals store energy during the colder seasons.
In the near-surface layers, there are many large, fast carnivores as well as an immense variety of planktonic animals, which feed on plankton (small, free-floating plants or animals) by filtering them from currents of water that pass through a specialized anatomical structure. These filter-feeders thrive in the well-illuminated surface waters because oceans have so many very small organisms, from bacteria to large algae to larval crustaceans. Even fishes can become successful filter-feeders in some circumstances. Although the vast majority of marine fishes are carnivores, in near-surface regions of high productivity the concentrations of larger phytoplankton (the plant component of plankton) are sufficient to support huge populations of filter-feeding sardines and anchovies. These small fishes use their gill filaments to strain out the algae that dominate such areas. Sardines and anchovies provide the basis for huge commercial fisheries as well as a food resource for large numbers of local carnivores, particularly seabirds. At a much larger scale, baleen whales and whale sharks are also efficient filter-feeders in productive coastal or polar waters, although their filtered particles comprise small animals such as copepods and krill rather than phytoplankton.
3.What can be inferred from paragraph 2 about fish?
A. Most fish feed on plankton.
B. Fish tend to avoid well-illuminated areas.
C. Most fish species are not filter-feeders.
D. Few fish species are successful in the near-surface layers.
4.According to paragraph 2, how do sardines and anchovies obtain food near the surface of the ocean?
A. They rely on the large quantities of food resources also available to local carnivores.
B. They capture the larvae of some crustaceans.
C. They feed on the organisms left over by commercial fisheries.
D. They obtain algae by using their gills as filters.
5.According to paragraph 2, in which of the following ways are baleen whales and whale sharks different from smaller fitter-feeders like sardines and anchovies?
A. They are not found in coastal waters.
B. They are caught by commercial fisheries.
C. They fitter small animals instead of phytoplankton.
D. They are not carnivores.

Filtering seawater for its particulate nutritional content can be an energetically demanding method of feeding, particularly when the current of water to be filtered has to be generated by the organism itself, as is the case for all planktonic animals. Particulate organic matter of at least 2.5 micrograms per cubic liter is required to provide a filter-feeding planktonic organism with a net energy gain. This value is easily exceeded in most coastal waters, but in the deep sea, the levels of organic matter range from next to nothing to around 7 micrograms per cubic liter. Even though mean levels may mask much higher local concentrations, it is still the case that many deep-sea animals are exposed to conditions in which a normal filter-feeder would starve.
6.Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.
A. An organism may obtain food particles from seawater when currents generated by the organism cause water to pass through its fitter
B. The nutritional content of the food particles in seawater is sufficient to meet the energy demands of most planktonic animals.
C. As planktonic animals require a lot of energy, they have to generate a current strong enough to bring them sufficient particles of food.
D. Organisms that filter seawater to meet their nutritional needs expend a lot of energy, especially those organisms that have to create their own currents.
There are, therefore, fewer successful filter-feeders in deep water, and some of those that are there have larger filtering systems to cope with the scarcity of particles. Another solution for such animals is to forage in particular layers of water where the particles may be more concentrated. Many of the groups of animals that typify the filter-feeding lifestyle in shallow water have deep-sea representatives that have become predatory. Their filtering systems, which reach such a high degree of development in shallow- water species, are greatly reduced. Alternative methods of active or passive prey capture have been evolved, including trapping and seizing prey, entangling prey, and sticky tentacles.
7.The word "scarcity" in the passage is closest in meaning to
A. speed
B. variety
C. lack
D. size
8.According to paragraph 4, deep-water filter-feeders have adopted all of the following ways to obtain food EXCEPT
A. developing larger filtering systems
B. capturing prey using sticky tentacles
C. swimming up to the surface at feeding time
D. searching in ocean layers that contain a substantial amount of particles
In the deeper waters of the oceans, there is a much greater tendency for animals to await the arrival of food particles or prey rather than to search them out actively (thus minimizing energy expenditure).  This has resulted in a more stealthy style of feeding, with the consequent emphasis on lures and/or the evolution of elongated appendages that increase the active volume of water controlled or monitored by the animal.  Another consequence of the limited availability of prey is that many animals have developed ways of coping with much larger food particles, relative to their own body size, than the equivalent shallower species can process.  Among the fishes there is a tendency for the teeth and jaws to become appreciably enlarged. In such creatures, not only are the teeth hugely enlarged and/or the jaws elongated but the size of the mouth opening may be greatly increased by making the jaw articulations so flexible that they can be effectively dislocated. Very large or long teeth provide almost no room for cutting the prey into a convenient size for swallowing, the fish must gulp the prey down whole.

9.Why does the author include the information that animals in the deep ocean place an "emphasis on lures" and have evolved "elongated appendages" ?
A. To argue against the view that animals in the deep ocean use more energy to find food than do animals in shallow waters
B. To emphasize the importance of an am mars ability to control a large volume of water
C. To identify some feeding strategies that animals have developed to minimize their energy expenditure
D. To give examples of body structures that help those animals move quickly in deep ocean waters
10.The phrase "coping with" in the passage is closest in meaning to
A. Absorbing
B. finding
C. approaching
D. managing
11.The word "flexible" in the passage is closest in meaning to
A. huge
B. adaptable
C. powerful
D. precise
12.According to paragraph 5, why do some fish swallow their prey whole?
A. Their teeth are too large to allow for cutting prey.
B. They have no jaw muscles to allow chewing.
C. Swallowing prey whole results in a higher net energy gain.
D. Chewing can cause their jaws to dislocate.
14.Directions: An introductory sentence for a brief summary of the passage is provided below Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage This question is worth 2 points. Ocean animals have developed various strategies for maximizing energy input from food.
A.Large carnivores near the ocean surface feed mainly on organic matter left over after it passes through the filters of the filter-feeders.
B.Even in deep ocean layers where prey is relatively hard to find, filter feeding is still the least energetically-demanding method of obtaining food.
C.Animals in deeper water have evolved strategies and body structures that allow them to use as little energy as possible in obtaining food.
D.Near the surface of the water, many animals obtain food by using specialized body parts to filter plankton from the water.
E.Filter-feeding is more common in shallow water, where there is a higher concentration of organic matter than there is in deeper water.
F.At deeper ocean levels plankton is relatively rare, requiring animals at those levels to actively search for their food sources.

TOEFL.READING.E45.Wind Pollination

Wind Pollination
Pollen, a powdery substance, which is produced by flowering plants and contains male reproductive cells, is usually carried from plant to plant by insects or birds, but some plants rely on the wind to carry their pollen. Wind pollination is often seen as being primitive and wasteful in costly pollen and yet it is surprisingly common, especially in higher latitudes. Wind is very good at moving pollen a long way; pollen can be blown for hundreds of kilometers, and only birds can get pollen anywhere near as far. The drawback is that wind is obviously unspecific as to where it takes the pollen. It is like trying to get a letter to a friend at the other end of the village by climbing onto the roof and throwing an armful of letters into the air and hoping that one will end up in the friend's garden. For the relatively few dominant tree species that make up temperate forests, where there are many individuals of the same species within pollen range, this is quite a safe gamble. If a number of people in the village were throwing letters off roofs, your friend would be bound to get one. By contrast, in the tropics, where each tree species has few, widely scattered individuals, the chance of wind blowing pollen to another individual is sufficiently slim that animals are a safer bet as transporters of pollen. Even tall trees in the tropics are usually not wind pollinated despite being in windy conditions. In a similar way, trees in temperate forests that are insect pollinated tend to grow as solitary, widely spread individuals.

1.The word "drawback" in the passage is closest in meaning to
A. other side of the issue

B. objection

C. concern

D. problem

2.Which of the following can be inferred from paragraph 1 about pollen production?
A. Pollen production requires a significant investment of energy and resources on the part of the plant.

B. The capacity to produce pollen in large quantities is a recent development in the evolutionary history of plants.

C. Plants in the tropics generally produce more pollen than those in temperate zones.

D. The highest levels of pollen production are found in plants that depend on insects or birds to carry their pollen.

3.According to paragraph 1, wind-pollinated trees are most likely to be found
A. in temperate forests

B. at lower latitudes

C. in the tropics

D. surrounded by trees of many different species

4.Paragraph 1 supports which of the following as the reason animals are a safer bet than wind as pollinators when the individual trees of a species are widely separated?
A. Animals tend to carry pollen from a given flower further than the wind does.

B. Animals serve as pollinators even where there is little wind to disperse the pollen.

C. An animal that visits a flower is likely to deliberately visit other flowers of the same species and pollinate them.

D. Birds and insects fly in all directions, not just the direction the wind is blowing at a given moment.

5.In paragraph 1, the author compares pollen moved by wind with letters thrown off roofs in order to
A. explain why there are relatively few species of trees that depend on wind pollination

B. compare natural, biological processes with human social practices

C. make a point about the probability of wind-blown pollen reaching a tree of the same species

D. argue against the common assumption that the tallest trees are the most likely to employ wind pollination

Since wind-pollinated flowers have no need to attract insects or other animals, they have dispensed with bright petals, nectar, and scent. These are at best a waste and at worst an impediment to the transfer of pollen in the air. The result is insignificant-looking flowers and catkins (dense cylindrical clusters of small, petalless flowers).

6.Paragraph 2 suggests that wind-pollinated plants do not have bright petals, nectar, and scent for which TWO of the following reasons? To receive credit, you must select TWO answers.
A. They interfere with pollination by wind.

B. They are easily damaged by wind.

C. They are unnecessary.

D. They reduce the amount of pollen that can be produced

Wind pollination does, of course, require a lot of pollen.  Birch and hazel trees can produce 5.5 and 4 million grains per catkin, respectively . There are various adaptations to help as much of the pollen go as far as possible.  Most deciduous wind-pollinated trees (which shed their leaves every fall) produce their pollen in the spring while the branches are bare of leaves to reduce the surrounding surfaces that “compete" with the stigmas (the part of the flower that receives the pollen) for pollen.  Evergreen conifers, which do not shed their leaves, have less to gain from spring flowering, and, indeed, some flower in the autumn or winter.

7.The word "respectively" in the passage is closest in meaning to
A. over time

B. separately

C. in that order

D. consistently

8.According to paragraph 3, why do most deciduous wind-pollinated trees produce their pollen in the spring?
A. To avoid competing with evergreen conifers, which flower in the fall or winter

B. So that the leaves of the trees receiving the pollen will not prevent the pollen from reaching the trees' stigmas

C. Because they do not have enough energy to produce new leaves and pollen at the same time

D. In order to take advantage of the windiest time of year

Pollen produced higher in the top branches is likely to go farther: it is windier (and gustier) and the pollen can be blown farther before hitting the ground. Moreover, dangling catkins like hazel hold the pollen in until the wind is strong enough to bend them, ensuring that pollen is only shed into the air when the wind is blowing hard. Weather is also important. Pollen is shed primarily when the air is dry to prevent too much sticking to wet surfaces or being knocked out of the air by rain. Despite these adaptations, much of the pollen fails to leave the top branches, and only between 0.5 percent and 40 percent gets more than 100 meters away from the parent. But once this far, significant quantities can go a kilometer or more. Indeed, pollen can travel many thousands of kilometers at high altitudes. Since all this pollen is floating around in the air, it is no wonder that wind-pollinated trees are a major source of allergies.

9.According to paragraph 4, which of the following is NOT an adaptation that helps ensure that pollen travels as far as possible?
A. Pollen-producing flowers and catkins are located at or near the top of the tree.

B. Trees grow at least 100 meters away from each other.

C. Dangling catkins release pollen only when the wind is blowing hard.

D. Pollen is not released during rain storms or when the air is damp.

10.The word "significant" in the passage is closest in meaning to
A. sufficient

B. considerable

C. increasing

D. small

11.The phrase "no wonder" in the passage is closest in meaning to
A. unsurprising

B. understandable

C. well-known

D. unfortunate

Once the pollen has been snatched by the wind, the fate of the pollen is obviously up to the vagaries of the wind, but not everything is left to chance. Windborne pollen is dry, rounded, smooth, and generally smaller than that of insect-pollinated plants. But size is a two-edged sword. Small grains may be blown farther but they are also more prone to be whisked past the waiting stigma because smaller particles tend to stay trapped in the fast-moving air that flows around the stigma. But stigmas create turbulence, which slows the air speed around them and may help pollen stick to them.

12.Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.
A. Because smaller particles tend to stay trapped in the fast moving air, they are blown much farther than other grains.

B. Smaller particles are trapped by the stigma when fast-moving air flows past it.

C. Small particles that are whisked past the waiting stigma gain speed and are often trapped in the fast-moving air.

D. While smallness helps pollen travel farther, it also makes it more likely to be blown past the stigma.

14.Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points. Some plants depend on the wind to carry their pollen.
A.Because there are few trees in temperate forests, it is safer to transport pollen by insects or birds.

B.Wind pollination is a safe reproductive strategy for trees in temperate forests where there are only a few dominant species and, therefore, many individuals of the same species.

C.Wind pollination requires production of a large amount of pollen, which must be released at the right time and under the right conditions to extend its range.

D.Most wind-pollinated trees are deciduous because evergreen needles compete with the stigma for pollen, making wind pollination uncertain.

E.Wind-pollinated plants usually have small petalless flowers which often grow in catkins that produce a very fine-grained pollen.

F.Wind-pollinated trees must grow in regions that are only moderately windy because strong winds will blow the tiny pollen grains past the stigma.

TITANIC 288

288 EXT. OCEAN
Jack and Rose drift under the blazing stars. The water is glassy, with only
the faintest undulating swell. Rose can actually see the stars reflecting
on the black mirror of the sea.
Jack squeezes the water out of her long coat, tucking it in tightly around
her legs. He rubs her arms. His face is chalk with in the darkness. A low
MOANING in the darknes around them.
                                   ROSE
It's getting quiet.
                                   JACK
Just a few more minutes. It'll take them a while to get the boats
organized...
Rose is unmoving, just staring into space. She knows the truth. There won't
be any boats. Behind Jack she sees that Officer Wilde has stopped moving.
He is slumped in his lifejacket, looking almost asleep. He has died of
exposure already.
                                   JACK
I don't know about you, but I intend to write a strongly worded letter to
the White Star Line about all this.
She laughs weakly, but it sounds like a gasp of fear. Rose finds his eyes
in the dim light.
                                   ROSE
I love you Jack.
He takes her hand.
                                   JACK
No... don't say your good-byes, Rose. Don't you give up. Don't do it.
                                   ROSE
I'm so cold.
                                   JACK
You're going to get out of this... you're going to go on and you're going
to make babies and watch them grow and you're going to die an old lady,
warm in your bed. Not here. Not this night. Do you understand me?
                                   ROSE
I can't feel my body.
                                   JACK
Rose, listen to me. Listen. Winning that ticket was the best thing that
ever happened to me.
Jack is having trouble getting the breath to speak.
                                   JACK
It brought me to you. And I'm thankful, Rose. I'm thankful.
His voice is trembling with the cold which is working tis way to his heart.
But his eyes are unwavering.
                                   JACK
You must do me this honor... promise me you will survive... that you will
never give up... no matter what happens... no matter how hopeless...
promise me now, and never let go of that promise.
                                   ROSE
I promise.
                                   JACK
Never let go.
                                   ROSE
I promise. I will never let go, Jack. I'll never let go.
She grips his hand and they lie with their heads together. It is quiet now,
except for the lapping of the water.

TOEFL.READING.E45.Microscopes The Beringia Landscape

Microscopes The Beringia Landscape


During the peak of the last ice age, northeast Asia (Siberia) and Alaska were connected by a broad land mass called the Bering Land Bridge. This land bridge existed because so much of Earth’s water was frozen in the great ice sheets that sea levels were over 100 meters lower than they are today. Between 25,000 and 10,000 years ago, Siberia, the Bering Land Bridge, and Alaska shared many environmental characteristics. These included a common mammalian fauna of large mammals, a common flora composed of broad grasslands as well as wind-swept dunes and tundra, and a common climate with cold, dry winters and somewhat warmer summers. The recognition that many aspects of the modern flora and fauna were present on both sides of the Bering Sea as remnants of the ice-age landscape led to this region being named Beringia.

1.The word "remnants" in the passage is closest in meaning to
A. remains

B. evidence

C. results

D. reminders

It is through Beringia that small groups of large mammal hunters, slowly expanding their hunting territories, eventually colonized North and South America. On this archaeologists generally agree, but that is where the agreement stops. One broad area of disagreement in explaining the peopling of the Americas is the domain of paleoecologists, but it is critical to understanding human history: what was Beringia like?

2.The word "domain" in the passage is closest in meaning to
A. field of expertise

B. challenge

C. interest

D. responsibility

The Beringian landscape was very different from what it is today. Broad, windswept valleys; glaciated mountains; sparse vegetation; and less moisture created a rather forbidding land mass. This land mass supported herds of now-extinct species of mammoth, bison, and horse and somewhat modern versions of caribou, musk ox, elk, and saiga antelope. These grazers supported in turn a number of impressive carnivores, including the giant short-faced bear, the saber-tooth cat, and a large species of lion.

3.According to paragraph 3, all of the following are true of the Beringian landscape EXCEPT.
A. There was little vegetation.

B. The mammal species there all survived into modern versions.

C. The climate was drier than it is today.

D. There were mountains with glaciers.

4.The purpose of paragraph 3 is to
A. contrast today’s Beringian landscape with other landscapes in the American continent

B. describe the Beringian landscape during the last ice age

C. explain why so many Beringian species became extinct during the last ice age

D. summarize the information about Beringia that historians agree on

The presence of mammal species that require grassland vegetation has led Arctic biologist Dale Guthrie to argue that while cold and dry, there must have been broad areas of dense vegetation to support herds of mammoth, horse, and bison. Further, nearly all of the ice-age fauna had teeth that indicate an adaptation to grasses and sedges; they could not have been supported by a modern flora of mosses and lichens. Guthrie has also demonstrated that the landscape must have been subject to intense and continuous winds, especially in winter. He makes this argument based on the anatomy of horse and bison, which do not have the ability to search for food through deep snow cover. They need landscapes with strong winds that remove the winter snows, exposing the dry grasses beneath. Guthrie applied the term “ mammoth steppe" to characterize this landscape.

5.The word "continuous" in the passage is closest in meaning to
A. unpredictable

B. very cold

C. dangerous

D. uninterrupted

6.Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.
A. According to biologist Dale Guthrie, mammal species require broad areas of vegetation to survive.

B. Dale Guthrie is an Arctic biologist who argued that broad areas of dense vegetation were surely enough to attract mammals such as mammoth, horse, and bison to Beringia.

C. Dale Guthrie argued that Beringia, though cold and dry, must have had enough dense vegetation to support the herds of mammoth, horse, and bison that lived there.

D. As long as Beringia was cold and dry, argued Dale Guthrie, dense vegetation grew in order to support the herds of mammoth, horse, and bison—the mammal species present there.

7.According to paragraph 4, Guthrie believes that the teeth of ice-age fauna support which of the following conclusions?
A. Large mammals would not have been able to survive in the Beringian landscape.

B. Grasslands were part of the Beringian landscape.

C. Strong winds exposed dry grasses under the snow.

D. Horses and bison did not have the ability to search for food through deep snow cover.

8.According to paragraph 4, which of the following statements is true of the relationship between ice-age Benngian animals and their environment?
A. When present in sufficient quantities, lichens and mosses provide enough nutrients to satisfy the needs of herds of large mammals.

B. The anatomy of certain animals present in that environment provides information about the intensity of winds there at that time.

C. The structure of the teeth of most ice-age fauna indicates that they preyed on animals such as the mammoth, horse, and bison.

D. Horses and bison are large enough that their feet can easily penetrate deep snow and uncover areas where they can feed on plant material.

In contrast, Paul Colinvaux has offered a counterargument based on the analysis of pollen in lake sediments dating to the last ice age. He found that the amount of pollen recovered in these sediments is so low that the Beringian landscape during the peak of the last glaciation was more likely to have been what he termed a "polar desert," with little or only sparse vegetation, in no way was it possible that this region could have supported large herds of mammals and thus, human hunters. Guthrie has argued against this view by pointing out that radiocarbon analysis of mammoth, horse, and bison bones from Beringian deposits revealed that the bones date to the period of most intense glaciation.

9.In paragraph 5, the amount of pollen in Beringian lake sediments from the last ice age is used to explain
A. how long the ice age lasted

B. how important pollen is as a source of food

C. how many different kinds of plants produce pollen

D. how little vegetation must have been present at that time

10.According to paragraph 5, how did Dale Guthrie use the information about radiocarbon analysis of bones fromBeringian deposits?
A. To suggest that Colinvaux should have used different methods to measure the amount of pollen in ice-age lake sediments

B. To argue that the large Beringian mammals must have eaten plants that produce little, if any, pollen

C. To show that the conclusions that Colinvaux drew from the analysis of pollen in ice-age lake sediments cannot be correct

D. To explain why so-called polar deserts are incapable of supporting such large animals as mammoth, horse, and bison

The argument seemed to be at a standstill until a number of recent studies resulted in a spectacular suite of new finds. The first was the discovery of a 1,000-square-kilometer preserved patch of Beringian vegetation dating to just over 17,000 years ago—the peak of the last ice age. The plants were preserved under a thick ash fall from a volcanic eruption. Investigations of the plants found grasses, sedges, mosses, and many other varieties in a nearly continuous cover, as was predicted by Guthrie. But this vegetation had a thin root mat with no soil formation, demonstrating that there was little long-term stability in plant cover, a finding supporting some of the arguments of Colinvaux. A mixture of continuous but thin vegetation supporting herds of large mammals is one that seems plausible and realistic with the available data.

11.The word "plausible" in the passage is closest in meaning to
A. preferable

B. practical

C. reasonable

D. advantageous

12.Which of the following best describes the organization of paragraph 6?
A. Two contrasting views are presented, and a study that could decide between them is proposed

B. An argument is offered, and reasons both for and against the argument are presented

C. A claim is made, and a study supporting the claim is described

D. New information is presented, and the information is used to show that two competing explanations can each be seen as correct in some way.

14.Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points. During the last ice age, human hunters pursued large mammals across Beringia, a land whose climatic characteristics have been in dispute.
A.Strong evidence indicates that large mammals like mammoth and bison survived in the harsh ice-age Beringian landscape.

B.Carnivores such as the saber-tooth cat were primarily responsible for the disappearance of the largest of the grazing animals, but the harsh winters caused some grazers to die of starvation.

C.The discovery that grasses, sedges, and mosses survived under the thick ash from a large volcanic eruption proved that the ice-age Beringian plant cover was extremely resistant to climatic extremes.

D.Benngian mammals crossed easily from northeastern Asia to Alaska across the Bering Land Bridge, though there are indications that they usually went back to Asia for the brief, but warm, summers.

E.Analyses of ice-age sediments uncovered very small amounts of pollen, suggesting that Beringia lacked the quantity of vegetation needed to support large herds of mammals.

F.Recent discoveries suggest that shallow-rooted plants created a fairly continuous cover over ice-age Beringia, though the cover most likely was variable and uncertain in any one location.