大学四级-20及答案解析.doc

1、大学四级-20 及答案解析(总分：713.00，做题时间：90 分钟)一、BPart Writing(总题数：1，分数：106.00)1.你的外国朋友 Pablo 要来你的家乡玩，对此用一封信来表达你的欢迎； 2对家乡做一个简要的介绍。（分数：106.00）_二、BPart Reading (总题数：1，分数：70.00)Directions: In this part, you will have 15 minutes to go over the passage quickly and answer the questions on Answer Sheet 1. For question

2、s 1-7, choose the best answer from the four choices marked IA , B, C and D. For questions 8-10, complete the sentences with the information given in the passage.Can We Replant the Planets Rainforests?Its hard not to be impressed by rainforests. Towering, aged trees called emergents stretch almost 25

3、0 feet (76 meters) into the air, surpassing the interwoven canopy that both covers and houses more than half of the worlds species. Though rainforests contain nearly half of all the planets trees, they only cover about 7 percent of the surface of the land.Despite the importance of rainforests, defor

4、estation practices continue. Though the term can apply to natural causes like forest fires, its commonly linked to human activities, like logging, agriculture and mining-all important for our economy. But by stripping (剥夺) the land of these resources, we must accept the consequences of our actions.

5、Chopping down rainforests increases the likelihood of soil erosion, landslides and flooding. It also decreases biodiversity and medical resources. More than 25 percent of modern medicine is derived from rainfurest plants, and only i percent of rainforest plant species have been studied for potential

6、 medicinal uses. Deforestation also destroys the homelands of indigenous cultures and affects the livelihoods of millions of other people, many of whom live in the worlds poorest regions.In an effort to counteract this destruction, conservation efforts are blossoming across the globe. Among these ar

7、e reforestation projects, aimed at increasing the amount of living trees and physically linking remaining forests together, to combat habitat loss and prevent species extinction.There are many challenges facing these projects. Firstly, rainforests are full of ancient, gigantic trees; these arent the

8、 saplings you buy at your local nursery. Much of the action of a rainforests ecosystem takes place in the lofty upper reaches, which can present problems for reforestation efforts since towering trees take decades to grow. Secondly, rainforest trees closely rely on their evolutionary playmates-the s

9、urrounding flora and fauna-to create the delicate conditions needed to sustain functions such as nutrient cycles and pollination.So while rainforests provide a flourishing (欣欣向荣) habitat for life, the success of that habitat relies on a fragile balance of ecological factors. Take away the trees and

10、you have a major problem. But if the soils bacteria and other microorganisms (微生物), which break down the nutrient-rich organic matter that tumbles to the dark forest floor, are also eliminated, the rainforest is destroyed. If the insects and birds that act as critical pollinators go extinct, life wi

11、ll falter.So, can we push up our sleeves, grab a shovel, dig in and just start replanting the rainforests? To a certain extent, we can. However, while efforts at reforestation have significant value, theyre usually not as crucial as preserving existing rainforests. Rainforest conservation is just as

12、 important as trying to reforest other areas.Reforestation can be accomplished by nature, by humans or through a combination of the two. Some reforestation efforts focus on growing forests quickly because these woodlands are key to many of Earths natural cycles, such as the carbon and water cycles.

13、Replanting deforested land with quick-growing exotic tree species, like eucalyptus or Australian acacia, can help solve immediate problems such as soil erosion and elevated carbon levels.However, exotic trees may make the land unsuitable for future rainforest cultivation by changing the soils origin

14、al characteristics. Scientists need to study individual situations to determine what type of impact each foreign species will make on the areas microbial life, and what the appropriate choices are for reforestation. On a positive note, fast-growing secondary forests and tree farms can replace primar

15、y forests as a source for agricultural and energy needs. A primary forest is basically one thats undisturbed by humans and has suffered very few ecological disruptions (中断). There are several other names for a primary forest, such as old growth and primeval forest. A secondary forest is one that has

16、 regrown after a destructive event, like a fire or logging. Primary forests usually have much higher levels of biodiversity than secondary ones, which is part of the reaso a conservationists are trying to save old growth.In areas where deforestation is severe, remaining patches of primary forests ar

17、e often located at great distances from other surviving rainforests or reforested regions. This makes animal survival and recolonization, as well as plant cross-pollination, difficult and can impede efforts to sustain actual rainforest ecology. Although the parcels of vegetative land can increase th

18、e chance of some species short-term survival, researchers say the species are likely doomed to extinction over the long term.One-way conservationists seek to protect rainforest species is to reforest the corridors of trees that lie between rainforest parce s. This gives plants and animals access to

19、a larger habitat and the chance to mix with other populations, which can boost their ,genetic diversity and help prevent extinction through isolation for most species. Conservationists can help cultivate these arborual arteries into supportable rainforest habitats by working to have these corridors

20、widened. The wider the corridors are, the safer they become for migrating animals to use.Its also important to reforest and enlarge areas adjacent to these surviving parcels. This provides an easy means for specie s to inhabit new territory and expand viable rainforest ecology.Researchers are explor

21、ing several options for improving and easing reforestation efforts. One inventive method involves bats. nstalling man-made bat roosts in deforested areas can encourage these uniquely flight-enabled mammals (like the spectacled flying fox ) to spread seeds and begin the process of rainforest regenera

22、tion. Activities like installing bat roosts are examples of how people are a part of natural reforestation efforts.Reforestation efforts are sprouting up all around the world. Numerous conservation groups are working to preserve, enlarge and connect the worlds rainforests. Lets take a closer look at

23、 some of those projects.Rwandas government and various ecological groups are paying special attention to the Gishwati Forest Reserve. Once a vast rainforest, activities such as deforestation and refugee resettlement reduced it to a fraction of its original size around the turn o:“ the century. Since

24、 then, reforestation has somewhat increased the size of the forest, but it remains a sliver of its original size.A project called the Rwandan National Conservation Park is gaining momentum, and those people involved with the projec are working to bring the rainforest back and connect it with larger,

25、 surviving rainforests nearby. These individuals and organizations are looking to accomplish this through the use of wide tree corridors. They also plan to increase the acreage of the coie forest and study the ecology of the forests animals, particularly its chimpanzees.（分数：70.00）(1).According the p

26、assage, what activities destroy the rainforests? A. All human activities. B. Forest fires, farming and mining. C. Logging only. D. Soil erosion, landslides and flooding.（分数：7.00）A.B.C.D.(2).Which of the following is one of the purposes these arent the saplings you buy at your local nursery. Much of

27、the action of a rainforests ecosystem takes place in the lofty upper reaches, which can present problems for reforestation efforts since towering trees take decades to grow. Secondly, rainforest trees closely rely on their evolutionary playmates-the surrounding flora and fauna-to create the delicate

28、 conditions needed to sustain functions such as nutrient cycles and pollination.So while rainforests provide a flourishing (欣欣向荣) habitat for life, the success of that habitat relies on a fragile balance of ecological factors. Take away the trees and you have a major problem. But if the soils bacter

29、ia and other microorganisms (微生物), which break down the nutrient-rich organic matter that tumbles to the dark forest floor, are also eliminated, the rainforest is destroyed. If the insects and birds that act as critical pollinators go extinct, life will falter.So, can we push up our sleeves, grab a

30、shovel, dig in and just start replanting the rainforests? To a certain extent, we can. However, while efforts at reforestation have significant value, theyre usually not as crucial as preserving existing rainforests. Rainforest conservation is just as important as trying to reforest other areas.Refo

31、restation can be accomplished by nature, by humans or through a combination of the two. Some reforestation efforts focus on growing forests quickly because these woodlands are key to many of Earths natural cycles, such as the carbon and water cycles. Replanting deforested land with quick-growing exo

32、tic tree species, like eucalyptus or Australian acacia, can help solve immediate problems such as soil erosion and elevated carbon levels.However, exotic trees may make the land unsuitable for future rainforest cultivation by changing the soils original characteristics. Scientists need to study indi

33、vidual situations to determine what type of impact each foreign species will make on the areas microbial life, and what the appropriate choices are for reforestation. On a positive note, fast-growing secondary forests and tree farms can replace primary forests as a source for agricultural and energy

34、 needs. A primary forest is basically one thats undisturbed by humans and has suffered very few ecological disruptions (中断). There are several other names for a primary forest, such as old growth and primeval forest. A secondary forest is one that has regrown after a destructive event, like a fire o

35、r logging. Primary forests usually have much higher levels of biodiversity than secondary ones, which is part of the reaso a conservationists are trying to save old growth.In areas where deforestation is severe, remaining patches of primary forests are often located at great distances from other sur

36、viving rainforests or reforested regions. This makes animal survival and recolonization, as well as plant cross-pollination, difficult and can impede efforts to sustain actual rainforest ecology. Although the parcels of vegetative land can increase the chance of some species short-term survival, res

37、earchers say the species are likely doomed to extinction over the long term.One-way conservationists seek to protect rainforest species is to reforest the corridors of trees that lie between rainforest parce s. This gives plants and animals access to a larger habitat and the chance to mix with other

38、 populations, which can boost their ,genetic diversity and help prevent extinction through isolation for most species. Conservationists can help cultivate these arborual arteries into supportable rainforest habitats by working to have these corridors widened. The wider the corridors are, the safer t

39、hey become for migrating animals to use.Its also important to reforest and enlarge areas adjacent to these surviving parcels. This provides an easy means for specie s to inhabit new territory and expand viable rainforest ecology.Researchers are exploring several options for improving and easing refo

40、restation efforts. One inventive method involves bats. nstalling man-made bat roosts in deforested areas can encourage these uniquely flight-enabled mammals (like the spectacled flying fox ) to spread seeds and begin the process of rainforest regeneration. Activities like installing bat roosts are e

41、xamples of how people are a part of natural reforestation efforts.Reforestation efforts are sprouting up all around the world. Numerous conservation groups are working to preserve, enlarge and connect the worlds rainforests. Lets take a closer look at some of those projects.Rwandas government and va

42、rious ecological groups are paying special attention to the Gishwati Forest Reserve. Once a vast rainforest, activities such as deforestation and refugee resettlement reduced it to a fraction of its original size around the turn o:“ the century. Since then, reforestation has somewhat increased the s

43、ize of the forest, but it remains a sliver of its original size.A project called the Rwandan National Conservation Park is gaining momentum, and those people involved with the projec are working to bring the rainforest back and connect it with larger, surviving rainforests nearby. These individuals

44、and organizations are looking to accomplish this through the use of wide tree corridors. They also plan to increase the acreage of the coie forest and study the ecology of the forests animals, particularly its chimpanzees.（分数：70.00）(1).According the passage, what activities destroy the rainforests?

45、A. All human activities. B. Forest fires, farming and mining. C. Logging only. D. Soil erosion, landslides and flooding.（分数：7.00）A.B. C.D.解析：解析 根据题干信息词 activities 和 rainforests 定位到第二段前两句，即：尽管热带雨林非常重要，但是森林砍伐仍在继续。虽然有些是由于自然原因导致，如森林火灾，但是它与人类的活动密切相关，如对我们的经济举足轻重的砍伐业、农业和采矿业，故选 B。并不是所有的人类活动都会造成破坏，仅仅是砍伐也不符合，

46、选项 A、C 过于绝对，均排除。土壤侵蚀、山体滑坡及洪水是热带雨林遭到破坏后的后果而不是它们导致了热带雨林遭到破坏，排除 D。(2).Which of the following is one of the purposes &reforestation projects? A. To study the potential medicinal uses of trees. B.To protect the habitat and prevent species loss. C. To make full use of the rainforests. D. To protect the re

47、maining forests.（分数：7.00）A.B. C.D.解析：解析 根据题干信息词 reforestation projects 定位到第三段末句，即：重新造林项目的目的是增加现存树木的数量、把现留的热带雨林连接在一起，保护物种的栖息地，防止物种灭绝，故选 B。热带雨林植物的药用价值在第二段谈论其重要性时提到过，但不是本题中重新造林项目的目的，排除选项 A。选项 C(充分利用热带雨林)也不是该项目的目的，排除。选项 D(保护现存的热带雨林)应该是conservation efforts 之一，但不是本题重新造林项目的目的，排除。(3).What do rainforest tree

48、s tightly rely on? A. Saplings. B. Microorganisms. C. Flora and fauna. D. Insects and birds.（分数：7.00）A.B.C. D.解析：解析 根据题干信息词 rainforest trees 和 rely on 定位到第四段末句，文章中提到：热带雨林的树木与环绕其周围的植被和动物群密切相关，故选 C。选项 B(微小动植物)、D(昆虫和鸟类)包含在 C 中，只是植被和动物群的一部分而已。(4).Why are the quick-growing exotic tree species replanted i

49、n the deforested land? A. Because they can help prevent soil erosion. B. Because they are easy to survive. C. Because some of them are eucalyptus or Australian acacia. D. Because they look like ancient trees very much.（分数：7.00）A. B.C.D.解析：解析 根据题干信息词 quick-growing exotic tree species 定位到第七段末句，即：用生长快速的外来树种，如桉树或澳大利亚洋槐，来补植被任意砍伐的森林，可以帮助解决迫在眉睫的问题，如水土流失、二氧化碳 升高。选项 A(因为它们能帮助阻止水土流失)符合原文。选项 B(因为它们容易成活)、D(因