托福-47及答案解析.doc

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1、托福-47 及答案解析(总分：124.96，做题时间：90 分钟)一、BREADING/B(总题数：0，分数：0.00)Directions: Read the passage. Then answer the questions. Give yourself 20 minutes to complete this practice set.HABITATS AND CHIPMUNK SPECIESThere are eight chipmunk species in the Sierra Nevada mountain range, and most of them look pretty

2、much alike. But eight different species of chipmunks scurrying around a picnic area will not be found. Nowhere in the Sierra do all eight species occur together. Each species tends strongly to occupy a specific habitat type, within an elevational range, and the overlap among them is minimal.The eigh

3、t chipmunk species of the Sierra Nevada represent but a few of the 15 species found in western North America, yet the whole of eastern North America makes do with but one species: the Eastern chipmunk. Why are there so many very similar chipmunks in the West? The presence of tall mountains intersper

4、sed with vast areas of arid desert and grassland makes the West ecologically far different from the East. The West affords much more opportunity for chipmunk populations to become geographically isolated from one another, a condition of species formation. Also, there are more extremes in western hab

5、itats. In the Sierra Nevada, high elevations are close to low elevations, at least in terms of mileage, but ecologically they are very different.Most ecologists believe that ancient populations of chipmunks diverged genetically when isolated from one another by mountains and unfavorable ecological h

6、abitat. These scattered populations first evolved into racesadapted to the local ecological conditionsand then into species, reproductively isolated from one another. This period of evolution was relatively recent, as evidenced by the similar appearance of all the western chipmunk species.Ecologists

7、 have studied the four chipmunk species that occur on the eastern slope of the Sierra and have learned just how these species interact while remaining separate, each occupying its own elevational zone. The sagebrush chipmunk is found at the lowest elevation, among the sagebrush. The yellow pine chip

8、munk is common in low to mid-elevations and open conifer forests, including （分数：7.00）(1).Why does the author mention a “picnic area“ in paragraph 1? A. To identify a site where a variety of different species of chipmunks can be seen B. To support the point that each species of chipmunk inhabits a di

9、stinct location C. To emphasize the idea that all species of chipmunks have a similar appearance D. To provide an example of a location to which chipmunks are likely to scurry for food（分数：0.50）A.B.C.D.(2).The phrase “interspersed with“ in the passage is closest in meaning to A. distributed among B.

10、covered by C. positioned above D. evolved from（分数：0.50）A.B.C.D.(3).In paragraph 2, the author indicates that a large variety of chipmunk species exist in western North America because of A. a large migration of chipmunks from eastern North America in an earlier period B. the inability of chipmunks t

11、o adapt to the high mountainous regions of eastern North America C. the ecological variety and extremes of the West that caused chipmunks to become geographically isolated D. the absence of large human populations that discouraged species formation among chipmunks in the East（分数：0.50）A.B.C.D.(4).The

12、 word “diverged“ in the passage is closest in meaning to A. declined B. competed C. progressed D. separated（分数：0.50）A.B.C.D.(5).The phrase “one another“ in the passage refers to A. populations B. races C. ecological conditions D. species（分数：0.50）A.B.C.D.(6).Which of the sentences below best expresse

13、s the essential information in the highlighted sentence in paragraph 4? Incorrect choices change the meaning in important ways or leave out essential information. A. Ecologists studied how the geographic characteristics of the eastern slope of the Sierra influenced the social development of chipmunk

14、s. B. Ecologists learned exactly how chipmunk species separated from each other on the eastern slope of the Sierra relate to one another. C. Ecologists discovered that chipmunks of the eastern slope of the Sierra invade and occupy higher elevational zones when threatened by another species. D. Ecolo

15、gists studied how individual chipmunks of the eastern slope of the Sierra avoid interacting with others of their species.（分数：0.50）A.B.C.D.(7).Where does paragraph 4 indicate that the yellow pine chipmunk can be found in relationship to the other species of the eastern slope of the Sierra? A. Below t

16、he sagebrush chipmunk B. Above the alpine chipmunk C. At the same elevation as the sagebrush chipmunk D. Below the lodgepole chipmunk（分数：0.50）A.B.C.D.(8).The word “encroachment“ in the passage is closest in meaning to A. complete destruction B. gradual invasion C. excessive development D. substituti

17、on（分数：0.50）A.B.C.D.(9).Paragraph 5 mentions all of the following as true of the relationship of sagebrush chipmunks to their habitats EXCEPT: A. Sagebrush chipmunks are able to survive in any habitat of the Sierra Nevada. B. Sagebrush chipmunks occupy their habitat because of the absence of competit

18、ion from other chipmunks. C. Sagebrush chipmunks are better able to survive in hot temperatures than other species of chipmunks. D. Sagebrush chipmunks spend the warm season at the higher elevations of the alpine zone.（分数：0.50）A.B.C.D.(10).Which of the following statements is supported by the result

19、s of the experiment described at the end of paragraph 5? A. The habitat of the yellow pine chipmunk is a desirable one to other species, but the habitat of the sagebrush chipmunk is not. B. It was more difficult to remove sagebrush chipmunks from their habitat than it was to remove yellow pine chipm

20、unks from theirs. C. Yellow pine chipmunks and sagebrush chipmunks require the same environmental conditions in their habitats. D. The temperature of the habitat is not an important factor to either the yellow pine chipmunk or the sagebrush chipmunk.（分数：0.50）A.B.C.D.(11).According to paragraph 6, wh

21、y is the lodgepole chipmunk so protective of its habitat from competing chipmunks? A. It has specialized food requirements. B. It cannot tolerate cold temperatures well. C. It requires the shade provided by forest trees. D. It prefers to be able to move between areas that are downslope and upslope.（

22、分数：0.50）A.B.C.D.(12).The phrase “by virtue of“ in the passage is closest in meaning to A. in spite of B. because of C. unconcerned about D. with attention to（分数：0.50）A.B.C.D.(13).Look at the four squares that indicate where the following sentence can be added to the passage.Yet each species remains

23、within a fairly well-defined elevational zone.Where would the sentence best fit?A. Ecologists have studied the four chipmunk species that occur on the eastern slope of the Sierra and have learned just how these species interact while remaining separate, each occupying its own elevational zone. The s

24、agebrush chipmunk is found at the lowest elevation among the sagebrush. The yellow pine chipmunk is common in low to mid-elevations and open conifer forests, including and ponderosa and Jeffrey pine forests. The lodgepole chipmunk is found at higher elevations, among the lodgepoles, firs, and high-e

25、levation pines. The alpine chipmunk is higher still, venturing among the talus slopes, alpine meadows, and high-elevation pines and junipers. Yet each species remains within a fairly well-defined elevational zone. Obviously, the ranges of each species overlap. Why dont sagebrush chipmunks move into

26、the pine zones? Why dont alpine chipmunks move to lower elevations and share the conifer forests with lodgepole chipmunks? B. Ecologists have studied the four chipmunk species that occur on the eastern slope of the Sierra and have learned just how these species interact while remaining separate, eac

27、h occupying its own elevational zone. The sagebrush chipmunk is found at the lowest elevation, among the sagebrush. The yellow pine chipmunk is common in low to mid-elevations and open conifer forests, including and ponderosa and Jeffrey pine forests. The lodgepole chipmunk is found at higher elevat

28、ions, among the lodgepoles, firs, and high-elevation pines. The alpine chipmunk is higher still, venturing among the talus slopes, alpine meadows, and high-elevation pines and junipers. Obviously, the ranges of each species overlap. Yet each species remains within a fairly well-defined elevational z

29、one. Why dont sagebrush chipmunks move into the pine zones? Why dont alpine chipmunks move to lower elevations and share the conifer forests with lodgepole chipmunks? C. Ecologists have studied the four chipmunk species that occur on the eastern slope of the Sierra and have learned just how these sp

30、ecies interact while remaining separate, each occupying its own elevational zone. The sagebrush chipmunk is found at the lowest elevation, among the sagebrush. The yellow pine chipmunk is common in low to mid-elevations and open conifer forests, including （分数：0.50）A.B.C.D.(14).Directions: An introdu

31、ctory 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 mi

32、nor ideas in the passage.Write your answer choices in the spaces where they belong. You can either write the letter of your answer choice or you can copy the sentence.A variety of chipmunk species inhabit western North America._Answer ChoicesA. Ecological variation of the Sierra Nevada resulted in t

33、he differentiation of chipmunk species.B. Only one species of chipmunk inhabits eastern North America.C. Although chipmunk species of the Sierra Nevada have the ability to live at various elevations, each species inhabits a specifically restricted one.D. Chipmunks aggressively defend their habitats

34、from invasion by other species of chipmunks.E. Experimental studies indicate that sagebrush chipmunks live in the desert because of their physiological requirements.F. The most aggressive of the chipmunk species is the lodgepole chipmunk.（分数：0.50）填空项 1:_Directions: Read the passage. Then answer the

35、questions. Give yourself 20 minutes to complete this practice set.CETACEAN INTELLIGENCEWe often hear that whales, dolphins, and porpoises are as intelligent as humans, maybe even more so. Are they really that smart? There is no question that cetaceans are among the most intelligent of animals. Dolph

36、ins, killer whales, and pilot whales in captivity quickly learn tricks. The military has trained bottlenose dolphins to find bombs and missile heads and to work as underwater spies.This type of learning, however, is called conditioning. The animal simply learns that when it performs a particular beh

37、avior, it gets a reward, usually a fish. Many animals, including rats, birds, and even invertebrates, can be conditioned to perform tricks. We certainly dont think of these animals as our mental rivals. Unlike most other animals, however, dolphins quickly learn by observations and may spontaneously

38、imitate human activities. One tame dolphin watched a diver cleaning an underwater viewing window, seized a feather in its beak, and began imitating the divercomplete with sound effects! Dolphins have also been seen imitating seals, turtles, and even water-skiers.Given the seeming intelligence of cet

39、aceans, people are always tempted to compare them with humans and other animals. Studies on discrimination and problem-solving skills in the bottlenose dolphin, for instance, have concluded that its intelligence lies “somewhere between that of a dog and a chimpanzee.“ Such comparisons are unfair. It

40、 is important to realize that intelligence is a very human concept and that we evaluate it in human terms. After all, not many people would consider themselves stupid because they couldnt locate and identify a fish by its echo. Why should we judge cetaceans by their ability to solve human problems?B

41、oth humans and cetaceans have large brains with an expanded and distinctively folded surface, the cortex. The cortex is the dominant association center of the brain, where abilities such as memory and sensory perception are centered. Cetaceans have larger brains than ours, but the ratio of brain to

42、body weight is higher in humans. Again, direct comparisons are misleading. In cetaceans it is mainly the portions of the brain associated with hearing and the processing of sound information that are expanded. The enlarged portions of our brain deal largely with vision and hand-eye coordination. Cet

43、aceans and humans almost certainly perceive the world in very different ways. Their world is largely one of sounds, ours one of sights.Contrary to what is depicted in movies and on television, the notion of “talking“ to dolphins is also misleading. Although they produce a rich repertoire of complex

44、sounds, they lack vocal cords and their brains probably process sound differently from ours. Bottlenose dolphins have been trained to make sounds through the blowhole that sound something like human sounds, but this is a far cry from human speech. By the same token, humans cannot make whale sounds.

45、We will probably never be able to carry on an unaided conversation with cetaceans.As in chimpanzees, captive bottlenose dolphins have been taught American Sign Language. These dolphins have learned to communicate with trainers who use sign language to ask simple questions. Dolphins answer back by pu

46、shing a “yes“ or “no“ paddle. They have even been known to give spontaneous responses not taught by the trainers. Evidence also indicates that these dolphins can distinguish between commands that differ from each other only by their word order, a truly remarkable achievement. Nevertheless, dolphins

47、do not seem to have a real language like ours. Unlike humans, dolphins probably cannot convey very complex messages.Observations of cetaceans in the wild have provided some insights on their learning abilities. Several bottlenose dolphins off western Australia, for instance, have been observed carry

48、ing large cone-shaped sponges over their beaks. They supposedly use the sponges for protection against stingrays and other hazards on the bottom as they search for fish to eat. This is the first record of the use of tools among wild cetaceans.Instead of “intelligence,“ some people prefer to speak of

49、 “awareness.“ In any case, cetaceans probably have a very different awareness and perception of their environment than do humans. Maybe one day we will come to understand cetaceans on their terms instead of ours, and perhaps we will discover a mental sophistication rivaling our own.（分数：6.96）(1).The author asks the question “Are they really that smart?“ for which of the following reasons? A. To question the notion that humans are t