托福-17及答案解析.doc

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1、托福-17 及答案解析(总分：121.08，做题时间：90 分钟)一、READING(总题数：0，分数：0.00)二、Part I(总题数：1，分数：6.50)Reading 1 “Exotic and Endangered Species“ When you hear someone bubbling enthusiastically about an exotic species, you can safely bet the speaker isnt an ecologist. This is a name for a resident of an established communi

2、ty that was deliberately or accidentally moved from its home range and became established elsewhere. Unlike most imports, which cant take hold outside their home range, an exotic species permanently insinuates itself into a new community.Sometimes the additions are harmless and even have beneficial

3、effects. More often, they make native species endangered species, which by definition are extremely vulnerable to extinction. Of all species on the rare or endangered lists or that recently became extinct, close to 70 percent owe their precarious existence or demise to displacement by exotic species

4、. Two examples are included here to illustrate the problem.During the 1800s, British settlers in Australia just couldnt bond with the koalas and kangaroos, so they started to import familiar animals from their homeland. In 1859, in what would be the start of a wholesale disaster, a northern Australi

5、an landowner imported and then released two dozen wild European rabbits (Oryctolagus cuniculus). Good food and good sport huntingthat was the idea. An ideal rabbit habitat with no natural predators was the reality.Six years later, the landowner had killed 20,000 rabbits and was besieged by 20,000 mo

6、re. The rabbits displaced livestock, even kangaroos. Now Australia has 200 to 300 million hippityhopping through the southern half of the country. They overgraze perennial grasses in good times and strip bark from shrubs and trees during droughts. You know where theyve been; they transform grassland

7、s and shrublands into eroded deserts. They have been shot and poisoned. Their warrens have been plowed under, fumigated, and dynamited. Even when all-out assaults reduced their population size by 70 percent, the rapidly reproducing imports made a comeback in less than a year. Did the construction of

8、 a 2,000-mile-long fence protect western Australia? No. Rabbits made it to the other side before workers finished the fence. In 1951, government workers introduced a myxoma virus by way of mildly infected South American rabbits, its normal hosts. This virus causes myxomatosis. The disease has mild e

9、ffects on South American rabbits that coevolved with the virus but nearly always had lethal effects on O. cuniculus. Biting insects, mainly mosquitoes and fleas, quickly transmit the virus from host to host. Having no coevolved defenses against the novel virus, the European rabbits died in droves. B

10、ut, as you might expect, natural selection has since favored rapid growth of populations of O. cuniculus resistant to the virus. In 1991, on an uninhabited island in Spencer Gulf, Australian researchers released a population of rabbits that they had injected with a calcivirus. The rabbits died quick

11、ly and relatively painlessly from blood clots in their lungs, hearts, and kidneys. In 1995, the test virus escaped from the island, possibly on insect vectors. It has been killing 80 to 95 percent of the adult rabbits in Australian regions. At this writing, researchers are now questioning whether th

12、e calcivirus should be used on a widespread scale, whether it can jump boundaries and infect animals other than rabbits (such as humans); and what the long-term consequences will be.A vine called kudzu (Pueraria lobata) was deliberately imported from Japan to the United States, where it faces no ser

13、ious threats from herbivores, pathogens, or competitor plants. In temperate parts of Asia, it is a well-behaved legume with a well-developed root system. It seemed like a good idea to use it to control erosion on hills and highway embankments in the southeastern United States. With nothing to stop i

14、t, though, kudzus shoots grew a third of a meter per day. Vines now blanket streambanks, trees, telephone poles, houses, and almost everything else in their path. Attempts to dig up or burn kudzu are futile. Grazing goats and herbicides help, but goats eat other plants, too, and herbicides contamina

15、te water supplies. Kudzu could reach the Great Lakes by the year 2040. On the bright side, a Japanese firm is constructing a kudzu farm and processing plant in Alabama. The idea is to export the starch to Asia, where the demand currently exceeds the supply. Also, kudzu may eventually help reduce log

16、ging operations. （分数：6.50）(1).Based on the information in paragraph 1, which of the following best explains the term “exotic species“?A. Animals or plants on the rare species listB. A permanent resident in an established communityC. A species that has been moved to a different communityD. An import

17、that fails to thrive outside of its home range（分数：0.50）A.B.C.D.(2).The word itself in the passage refers toA. most importsB. new communityC. home rangeD. exotic species（分数：0.50）A.B.C.D.(3).The word bond in the passage is closest in meaning toA. moveB. connectC. liveD. fight（分数：0.50）A.B.C.D.(4).Accor

18、ding to the author, why did the plan to introduce rabbits in Australia fail?A. The rabbits were infected with a contagious virus.B. Most Australians did not like the rabbits.C. No natural predators controlled the rabbit population.D. Hunters killed the rabbits for sport and for food.（分数：0.50）A.B.C.D

19、.(5).All of the following methods were used to control the rabbit population in Australia EXCEPTA. They were poisoned.B. Their habitats were buried.C. They were moved to deserts.D. They were surrounded by fences.（分数：0.50）A.B.C.D.(6).Whydoes the author mention mosquitoes and fleas in paragraph 5?A. B

20、ecause they are the origin of the myxoma virusB. Because they carry the myxoma virus to other animalsC. Because they die when they are infected by myxomaD. Because they have an immunity to the myxoma virus（分数：0.50）A.B.C.D.(7).According to paragraph 6, the Spencer Gulf experiment was dangerous becaus

21、eA. insect populations were exposed to a virusB. rabbits on the island died from a virusC. the virus may be a threat to humansD. some animals are immune to the virus（分数：0.50）A.B.C.D.(8).The word consequences in the passage is closest in meaning toA. stagesB. advantagesC. resultsD. increases（分数：0.50）

22、A.B.C.D.(9).Why does the author give details about the kudzu farm and processing plant in paragraph 8?A. To explain why kudzu was imported from abroadB. To argue that the decision to plant kudzu was a good oneC. To give a reason for kudzu to be planted in AsiaD. To offer partial solutions to the kud

23、zu problem（分数：0.50）A.B.C.D.(10).The word exceeds in the passage is closest in meaning toA. surpassesB. destroysC. estimatesD. causes（分数：0.50）A.B.C.D.(11).Which of the following statements most accurately reflects the authors opinion about exotic species?A. Exotic species should be protected by ecolo

24、gists.B. Importing an exotic species can solve many problems.C. Ecologists should make the decision to import an exotic species.D. Exotic species are often disruptive to the ecology.（分数：0.50）A.B.C.D.(12).Look at the four squares that show where the following sentence could be inserted in the passage

25、.Asians use a starch extract from kudzu in drinks, herbal medicines, and candy.Where could the sentence best be added?Click on a square to insert the sentence in the passage.A. Square .B. Square .C. Square .D. Square .（分数：0.50）A.B.C.D.(13). Directions: An introduction for a short summary of the pass

26、age appears below. Complete the summary by selecting the THREE answer choices that mention the most important points in the passage. Some sentences do not belong in the summary because they express ideas that are not included in the passage or are minor points from the passage.This question is worth

27、 2 points.Exotic species often require containment because they displace other species when they become established in a new environment._Answer ChoicesA. Rabbits were able to cross a fence 2,000 miles long that was constructed to keep them out of western Australia.B. Methods to control exotic speci

28、es include fences, viruses, burning, herbicides, natural predators, and harvesting.C. Rabbits that were introduced in Australia and kudzu which was introduced in the United States, are examples of species that caused problems.D. Researchers may be able to develop material from the kudzu vine that wi

29、ll be an alternative to wood pulp paper.E. The problem is that exotic species make native species vulnerable to extinction.F. A virus that is deadly to rabbits may have serious effects for other animals.（分数：0.50）填空项 1:_三、Part (总题数：2，分数：13.00)Reading 2 “Paleolithic Art“ The several millennia followin

30、g 30,000 B.C. saw a powerful outburst of artistic creativity. The artworks produced range from simple shell necklaces to human and animal forms in ivory, clay, and stone to monumental paintings, engravings, and relief sculptures covering the huge wall surfaces of caves. From the moment in 1879 that

31、cave paintings were discovered at Altamira, scholars have wondered why the hunter-artists of the Old Stone Age decided to cover the walls of dark caverns with animal images. Various answers have been given, including that they were mere decoration, but this theory cannot explain the narrow range of

32、subjects or the inaccessibility of many of the paintings. In fact, the remoteness and difficulty of access of many of the cave paintings and the fact they appear to have been used for centuries are precisely what have led many scholars to suggest that the prehistoric hunters attributed magical prope

33、rties to the images they painted. According to this argument, by confining animals to the surfaces of their cave walls, the artists believed they were bringing the beasts under their control. Some have even hypothesized that rituals or dances were performed in front of the images and that these rite

34、s served to improve the hunters luck. Still others have stated that the painted animals may have served as teaching tools to instruct new hunters about the character of the various species they would encounter or even to serve as targets for spears!By contrast, some scholars have argued that the mag

35、ical purpose of the paintings was not to facilitate the destruction of bison and other species. Instead, they believe prehistoric painters created animal images to assure the survival of the herds. Paleolithic peoples depended on for their food supply and for their clothing. A central problem for bo

36、th the hunting-magic and foodcreation theories is that the animals that seem to have been diet staples of Old Stone Age peoples are not those most frequently portrayed.Other scholars have sought to reconstruct an elaborate mythology based on the cave paintings, suggesting that Paleolithic humans bel

37、ieved they had animal ancestors. Still others have equated certain species with men and others with women and also found sexual symbolism in the abstract signs that sometimes accompany the images. Almost all of these theories have been discredited over time, and art historians must admit that no one

38、 knows the intent of these paintings. （分数：6.50）(1).According to paragraph 1, the cave art was difficult to find because the artistsA. were probably trying to keep their work a secret from their tribeB. could have begun their painting while they were confined in the cavesC. may have chosen a location

39、 deep in the caves to hold ceremoniesD. had to practice before they made images that more people could see（分数：0.50）A.B.C.D.(2).According to paragraph 1, Paleolithic people may have used cave art for all of the following purposes EXCEPTA. People may have danced in front of the images.B. Hunters could

40、 have used the figures for target practice.C. Shamans might have performed magical rituals in the caves.D. Animals may have been kept in the caves near the drawings.（分数：0.50）A.B.C.D.(3).The word access in the passage is closest in meaning toA. admissionB. meaningC. siteD. research（分数：0.50）A.B.C.D.(4

41、).The word facilitate in the passage is closest in meaning toA. specifyB. permitC. assistD. discover（分数：0.50）A.B.C.D.(5).The word those in the passage refers toA. peoplesB. staplesC. animalsD. theories（分数：0.50）A.B.C.D.(6).The word discredited in the passage is closest in meaning toA. not attentiveB.

42、 not believedC. not hopefulD. not organized（分数：0.50）A.B.C.D.(7).Which of the sentences below best expresses the information in the highlighted statement in the passage? The other choices change the meaning or leave out important information.A. It is true that the paintings were meaningful to the Pal

43、eolithic peoples.B. Doubtless, the Paleolithic peoples were the ones who made the paintings.C. There is no doubt about the meaning of the Paleolithic paintings.D. Paintings that had meaning for the Paleolithic peoples are doubtful.（分数：0.50）A.B.C.D.(8).How have some scholars interpreted the arrangeme

44、nt of lines into geometric shapes near the animal paintings?A. They are probably more pictures of animals.B. They may be an early writing system.C. It is possible that they have no significance.D. Probably most of the lines are scratches from age.（分数：0.50）A.B.C.D.(9).According to paragraph 4, why do

45、 scholars believe that the spots on the horses may represent a hunting scene?A. Other cave paintings near this one include hunting scenes.B. The spots are made of rocks that were attached to the wall.C. The spots are painted outside the horses forms as well as inside them.D. The primitive writing is

46、 interpreted as an accounting of a hunt.（分数：0.50）A.B.C.D.(10).According to paragraph 5, why did artists leave a positive imprint of their hands on cave paintings?A. It represents human beings in the cave paintings.B. It could have been a way for them to sign their work.C. It was a hunters handprint

47、among the herd of animals.D. It might have been a pleasing image without much meaning.（分数：0.50）A.B.C.D.(11).Which of the following statements most accurately reflects the authors opinion about the purpose of cave paintings?A. The cave paintings were part of a hunting ritual.B. Artists were honoring

48、their animal ancestors in cave paintings.C. The exact purpose of cave paintings is not known.D. Decoration was probably the main reason for painting in caves.（分数：0.50）A.B.C.D.(12).Look at the four squares that show where the following sentence could be inserted in the passage.At Altamira, for exampl

49、e, faunal remains show that red deer, not bison, were eaten.Where could the sentence best be added?Click on a square to insert the sentence in the passage.A. Square .B. Square .C. Square .D. Square .（分数：0.50）A.B.C.D.(13).Directions: An introduction for a short summary of the passage appears below. Complete the summary by selecting the THREE answer choices that mention the most important points in the passage. Some sentences do not belong in the summary because they express ideas th