大学英语四级249及答案解析.doc

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1、大学英语四级 249及答案解析(总分：746.52，做题时间：130 分钟)一、Writing (30 minutes)(总题数：1，分数：30.00)1.For this part, you are allowed 30 minutes to write an essay entitled On Conserving Energy. You should write at least 120 words following the outline given below in Chinese: 1. 能源短缺问题已非常严重； 2. 可以采取节能措施解决能源短缺问题； 3. 你的看法。 （分数

2、：30.00）_二、Reading Comprehensio(总题数：1，分数：71.00)Wetlands What are wetlands? Wetlands can be thought of as “biological supermarkets.“ They provide great volumes of food that attract many animal species. These animals use wetlands for part of or all of their life-cycle. Dead plant leaves and stems break

3、 down in the water to form small particles of organic material called “detritus.“ This enriched material feeds many small aquatic (水生的) insects, shellfish, and small fish that are food for larger predatory (食肉的) fish, reptiles, amphibians (两栖动物) , birds, and mammals. What are the functions and value

4、s of wetlands? Long regarded as wastelands, wetlands are now recognized as important features in the landscape that provide numerous beneficial services for people and for fish and wildlife. Some of these services, or functions, include water quality improvement, floodwater storage, fish and wildlif

5、e habitat, aesthetics, and biological productivity. These beneficial services, considered valuable to societies worldwide, are the result of the inherent and unique natural characteristics of wetlands. Water storage. Wetlands function like natural tubs or sponges, storing water and slowly releasing

6、it. This process slows the waters momentum and erosive potential, reduces flood heights, and allows for ground water recharge, which contributes to base flow to surface water systems during dry periods. Although a small wetland might not store much water, a network of many small wetlands can store a

7、n enormous amount of water. The ability of wetlands to store floodwaters reduces the risk of costly property damage and loss of lifebenefits that have economic value to us. For example, the U.S. Army Corps of Engineers found that protecting wetlands along the Charles River in Boston, Massachusetts,

8、saved $17 million in potential flood damage. Water filtration. After being slowed by a wetland, water moves around plants, allowing the suspended sediment to drop out and settle to the wetland floor. Nutrients from fertilizer application, manure, leaking septic tanks, and municipal sewage that are d

9、issolved in the water are often absorbed by plant roots and microorganisms in the soil. Other pollutants stick to soil particles. In many cases, this filtration process removes much of the waters nutrient and pollutant load by the time it leaves a wetland. Some types of wetlands are so good at this

10、filtration function that environmental managers construct similar artificial wetlands to treat storm water and wastewater. Biological productivity. Wetlands are some of the most biologically productive natural ecosystems in the world, comparable to tropical rain forests and coral reefs in their prod

11、uctivity and the diversity of species they support. Abundant vegetation and shallow water provide diverse habitats for fish and wildlife. Aquatic plant life flourishes in the nutrient-rich environment, and energy converted by the plants is passed up the food chain to fish, waterfowl, and other wildl

12、ife and to us as well. This function supports valuable commercial fish and shellfish industries. Fish and wildlife habitat. More than one-third of the United States threatened and endangered species live only in wetlands, and nearly half use wetlands at some point in their lives. Many other animals

13、and plants depend on wetlands for survival. For many animals and plants, like wood ducks and swamp rose, inland wetlands are the only places they can live. For others, such as black bear, raccoon (浣熊) , and deer, wetlands provide important food, water, or shelter. Many of the U.S. breeding bird popu

14、lationsincluding ducks, geese, woodpeckers, hawks, and many song-birdsfeed, nest, and raise their young in wetlands. Migratory waterfowl use coastal and inland wetlands as resting, feeding, breeding, or nesting grounds for at least part of the year. Recreation and aesthetics. Wetlands have recreatio

15、nal, historical, scientific, and cultural values. More than half of all U.S. adults hunt, fish, birdwatch or photograph wildlife. They spend a total of $59.5 billion annually. Painters and writers continue to capture the beauty of wetlands on canvas and paper, or through cameras, and video and sound

16、 recorders. Others appreciate these wonderlands through hiking, boating, and other recreational activities. Almost everyone likes being on or near the water; part of the enjoyment is the varied, fascinating life forms. How are wetlands protected? The federal government protects wetlands through regu

17、lations, economic incentives and disincentives, cooperative programs, and acquisition. Beyond the federal level, a number of states have enacted laws to regulate activities in wetlands, and some counties and towns have adopted local wetlands protection ordinances (法令) or have changed the way develop

18、ment is permitted. Most coastal states have significantly reduced losses of coastal wetlands through protective laws. Few states, however, have laws specifically regulating activities in inland wetlands, although some states and local governments have non-regulatory programs that help protect wetlan

19、ds. Recently, partnerships to manage whole watersheds have developed among federal, state, tribal, and local governments; nonprofit organizations; and private landowners. The goal of these partnerships is to implement comprehensive, integrated watershed protection approaches. A watershed approach re

20、cognizes the inter-connectedness of water, land, and wetlands resources and results in more complete solutions that address more of the factors causing wetland degradation. The government achieves the restoration of former or degraded wetlands under the Clean Water Act Section 404 program as well as

21、 through watershed protection initiatives. Together, partners can share limited resources to find the best solutions to protect and restore Americas natural resources. While regulation, economic incentives, and acquisition programs are important, they alone cannot protect the majority of our remaini

22、ng wetlands. Education of the public and efforts in conjunction with states, local governments, and private citizens are helping to protect wetlands and to increase appreciation of the functions and values of wetlands. The rate of wetlands loss has been slowing, but we still have work to do. You can

23、 be a part. Approximately 75 percent of wetlands are privately owned, so individual landowners are critical in protecting these national treasures. What can you do? Despite the efforts of governments and private conservation organizations, pressures that destroy wetlands will continue. The problems

24、of degradation of wetlands from pollution, urban encroachment, groundwater withdrawals, partial drainage, and other actions also require attention. Many opportunities exist for private citizens, corporations, government agencies, and other groups to work together to slow the rate of wetland loss and

25、 to improve the quality of our remaining wetlands. First, state and local governments need to be encouraged to establish programs to effectively protect wetlands, especially inland wetlands, within their borders. Second, because individual landowners and corporations own many of the nations wetlands

26、, they are in a key position to determine the fate of wetlands on their properties. Finally, all citizens, whether or not they own wetlands, can help protect wetlands by supporting wetlands conservation initiatives. Wetlands are an important part of our national heritage. Our economic well-being and

27、 quality of life largely depend on our nations wealth of natural resources, and wetlands are the vital link between our land and water resources. As wetlands are lost, the remaining wetlands become even more valuable. We have already lost many of our nations wetlands since America was first settled.

28、 We must now take positive steps to protect wetlands to ensure that the functions and related values they provide will be preserved for present and future generations. （分数：71.00）(1).The passage gives a general description of the functions and values and protection of wetlands.（分数：7.10）A.YB.NC.NG(2).

29、Wetlands can be thought of as “biological supermarkets“ because dead plant leaves and stems break down in the water.（分数：7.10）A.YB.NC.NG(3).Wetlands function like natural tubs or sponges, storing water and slowly releasing it.（分数：7.10）A.YB.NC.NG(4).Wetlands are some of the most biologically productiv

30、e natural ecosystems in the world, comparable to tropical rain forests and coral reefs in their productivity and the diversity of species they support.（分数：7.10）A.YB.NC.NG(5).More than half of the United States threatened and endangered species live only in wetlands, and nearly one-third use wetlands

31、 at some point in their lives.（分数：7.10）A.YB.NC.NG(6).Wetlands dont have any recreational, historical, scientific, and cultural values at all.（分数：7.10）A.YB.NC.NG(7).Eighteen states have enacted laws to regulate activities in wetlands.（分数：7.10）A.YB.NC.NG(8).The beneficial functions of wetlands, consid

32、ered valuable to societies worldwide, are the result of the inherent and unique_.（分数：7.10）_(9).Some types of wetlands are so good at this filtration function that environmental managers construct similar artificial wetlands to treat_.（分数：7.10）_(10).We should do all we can to protect wetlands to ensu

33、re that their functions and values will be preserved for_.（分数：7.10）_三、Listening Comprehens(总题数：1，分数：15.00)A.She has to post a letter instead.B.She has to turn down the mans request.C.Shes not sure if the computer is fixed.D.She cant send the message right now.A.He didnt get the book he needed.B.He h

34、ad no idea where the book was.C.The library is closed on weekends.D.He was not allowed to check out the book.A.Play a tape recorder.B.Take a picture.C.Repair a typewriter.D.Start a ear.A.The woman rejected the mans apology.B.The woman appreciated the mans offer.C.The man had forgotten the whole thin

35、g.D.The man had hurt the womans feelings.A.The woman is meeting the man at the airport.B.They are complaining about the poor airport service.C.They are discussing their plan for Christmas.D.The man is seeing the woman off.A.She plans to go to graduate school.B.She will drop out of school.C.She will

36、stop working and concentrate on her studies.D.She will take a part-time job.A.He needs another job as research assistant.B.He asked Professor Williams for assistance.C.He assists Professor Williams with his teaching.D.He is doing research with Professor Williams.A.She thought there were no tickets l

37、eft for the show.B.She thought the seats on the left side were fully occupied.C.The show was planned a long time ago.D.The audience were deeply impressed by the show.A.Mr. Longs briefing was unnecessarily long.B.The woman should have been more attentive.C.Mr. Longs briefing was not relevant to the m

38、ission.D.The woman neednt have attended the briefing.A.In a bank.B.In a school.C.In a clothing store.D.In a barbershop.四、Section B(总题数：2，分数：10.00)A.At a newspaper.B.At an advertising agency.C.At a furniture store.D.At a real estate office.A.A two-bedroom apartment.B.A sofa.C.A chair.D.A roommate.A.H

39、er phone number.B.The location of the apartment.C.The best time to call her.D.Her first name.A.$ 5.B.$ 15.C.$ 30D.$ 250.A.The man wants to obtain an international drivers license that he can use both in the U.S. and in his country.B.The man wants to take a drivers test to get an Arizona drivers lice

40、nse.C.The man wants to know whether he can use his international drivers license in Arizona.D.The man wants to fill out an application for an Arizona drivers license.A.Show his student ID and pay ten dollars.B.Use his international drivers license.C.Take a drivers test and apply for a limited licens

41、e.D.Show proof of temporary residence.A.Less than one year.B.Four years.C.Five years.D.Ten years.A.Fill out an application.B.Go back to the university to get his ID.C.Go to see his friend.D.Take a written exam and an eye exam.A.Early American Indians never ate roast corns.B.Early American Indians pl

42、anted lots of varieties of corns.C.Corn was important for early American Indians.D.Early American Indians ate corns fresh from the field.A.The history and traditions of early corn fanners.B.The growing cycle of Indian corn.C.Differences between the two corn harvests.D.Various ways to prepare corn.A.

43、It was first boiled and then dried.B.It was braided in bundles and steamed.C.It was dried and then ground into flour.D.It was roasted and wrapped in husks.A.Only half the worlds water can be used.B.The world population is increasing faster and faster.C.Half of the worlds water resources have been se

44、riously polluted.D.Humanity has not placed sufficient value on water resources.A.Be reduced to the minimum.B.Stimulate domestic demand.C.Reflect its real value.D.Take into account the occurrences of droughts.A.Build big lakes to store water.B.Construct big pumping stations.C.Build small and cheap ir

45、rigation systems.D.Channel water from nearby rivers to crop land.A.Guarantee full protection of the environment.B.Centralize the management of water resources.C.Increase the sense of responsibility of agencies at all levels.D.Encourage local and regional control of water resources.A.Clean.B.Powerful

46、.C.Cheap.D.Secure.A.31%.B.33%.C.58%.D.24%.A.Advantages of nuclear-generated electricity.B.Nuclear-and-coal-generated electricity.C.Nuclear-generated electricity becoming one of the basic props supporting the U. S. economy.D.U. S. energy independence.六、Section C(总题数：1，分数：10.00)I am amazed at some of

47、the statements made concerning Greg Louganiss decision not to (36) 1 the fact that he was HIV-positive. Although AIDS has been a (37) 2 word since the early 1980s, it appears that people still dont have a (38) 3 concerning the realities of the situation. Even though the ways of contracting HIV are w

48、ell-known, the general public still seems to react with (39) 4 fear for their own well-being when (40) 5 with someone who they know is HIV-positive or has AIDS. But because people who know that they are HIV-positive are very (41) 6 of this fact, they certainly will take more (42) 7 in protecting other people than will the millions of walking time (43) 8 who dont know their HIV status. (44) 9. That means (45) 10. E