大学英语四级-93及答案解析.doc

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1、大学英语四级-93 及答案解析(总分：100.00，做题时间：90 分钟)一、Reading Comprehensio(总题数：2，分数：100.00)Keep Our Seas CleanA. By the year 2050 it is estimated that the world“s population could have increased to around 12 billion. Of these, some 60 percent will live within 60 km of the sea. The agricultural and industrial activ

2、ities required to support this population will increase the already significant pressures on fertile coastal areas. Death and disease caused by polluted coastal waters costs the global economy US $12.8 billion a year. Plastic waste kills up to 1 million sea birds, 100,000 sea mammals and countless f

3、ish each year. B. One significant impact of human activity is marine pollution. The most visible and familiar is oil pollution caused by tanker accidents and tank washing at sea, and in addition to the gross visible short-term impacts, severe long-term problems can also result. In the case of the Ex

4、xon Valdez which ran onto a shore in Alaska in 1989, biological impacts from the oil spill can still be identified 15 years after the event. The Prestige which sank off the Spanish coast late in 2002, resulted in huge economic losses as it polluted more than 100 beaches in France and Spain and effec

5、tively destroyed the local fishing industry. C. Despite the scale and visibility of such impacts, the total quantities of pollutants entering the sea from the long line of catastrophic oil spills appeared small compared with those of pollutants introduced directly and indirectly from other sources,

6、including domestic sewage, industrial discharges, leakages from waste tips, urban and industrial run-off, accidents, spillages, explosions, sea dumping operations, oil production, mining, agriculture nutrients and pesticides, waste heat sources, and radioactive discharges. Land based sources are est

7、imated to account for around 44 percent of the pollutants entering the sea and atmospheric inputs account for an estimated 33 percent. By contrast, transport on the sea accounts for 12 percent. D. The impacts of pollution vary. Nutrient pollution from sewage discharges and agriculture can result in

8、unsightly and possibly dangerous “blooms“ of algae (藻类) in coastal waters. As these blooms die and decay they use up the oxygen in the water. This has led, in some areas, to “creeping dead zones“ (CDZ), where oxygen dissolved in the water falls to levels unable to sustain marine life. Industrial pol

9、lution also contributes to these dead zones. E. Radioactive (放射性的) pollution has many causes, including the normal operation of nuclear power stations, but by far the single biggest sources of man-made radioactive elements in the sea are the nuclear fuel reprocessing plants at La Hague in France and

10、 at Sellafield in the UK. Waste released from them has resulted in the widespread pollution of living marine resources over a wide area; radioactive elements traceable to reprocessing can be found in seaweeds as far away as the West Greenland Coast. F. Trace metal pollution from metal mining, produc

11、tion and processing industries can damage the health of marine plants and animals and render some seafoods unfit for human consumption. The contribution of human activities can be very significant: the amount of mercury introduced to the environment by industrial activities is around four times the

12、amount released through natural processes such as weathering and erosion (腐蚀). G. The input of man-made chemicals to the oceans potentially involves an overwhelming number of different substances. 63,000 different chemicals are thought to be in use worldwide with 3,000 accounting for 90 percent of t

13、he total production amount. Each year, anywhere up to 1,000 new synthetic chemicals may be brought onto the market. Of all these chemicals some 4,500 fall into the most serious category. These are known as persistent organic pollutants (POPs). They“re resistant to breakdown and have the potential to

14、 accumulate in the tissues of living organisms (all marine life), causing hormone disruption which can, in turn, cause reproductive problems, induce cancer, suppress the immune system and interfere with normal mental development in children. H. POPs can also be transported long distances in the atmo

15、sphere and deposited in cold regions. As a result, Inuit populations who live in the Arctic a long distance from the sources of these pollutants are among the most severely influenced people on the planet, since they rely on fat-rich marine food sources such as fish and seals. POPs are also thought

16、to be responsible for some polar bear populations failing to reproduce normally. Scarily, seafoods consumed by people living in warm and mild regions are also affected by POPs. Oily fish tend to accumulate POPs in their bodies and these can be passed to human consumers. When oily fish are rendered d

17、own into fish meal and fish oils and subsequently used to feed other animals, then this too can act as a pathway to humans. Farmed fish and shellfish, dairy cattle, poultry and pigs are all fed fish meal in certain countries, and so meat and dairy products as well as farmed and wild fish can act as

18、further sources of these chemicals to humans. I. The North and Baltic Seas also contain some of the world“s busiest shipping lanes. 200,000 ships cross the North Sea every year. Many goods transported by ships are hazardous (half the goods carried at sea can be described as dangerous) and loss of da

19、ngerous cargoes can result in damage to the marine environment. Chemical tank washings, discharge of oily wastes and wash waters are all significant sources of marine pollution. J. In addition there is always the risk of a major oil spill, a risk made worse by the fact that some of the tankers that

20、routinely travel through still have only one body-frame or have other technical defects and crews who are poorly educated. In November 2002, the Prestige oil tanker went down off the coast of Spain with 70,000 tons of oil on board which polluted 2,890 km of coastline. A few days earlier it had been

21、crossing the Baltic. K. Some sources of pollution have been brought under control by International legislation. Countries which signed the London Convention have agreed to stop the dumping of radioactive and industrial waste at sea. The OSPAR Convention regulates marine pollution in the North East A

22、tlantic Region while countries which signed the Stockholm Convention have committed themselves to the phase out of a number of persistent organic pollutants. Within the European Community, the Water Framework Directive may be expected to bring further reductions in polluting Inputs, although it will

23、 be over a very long time frame. The additional benefit of the new EU REACH (Registration Evaluation and Authorisation of Chemicals) initiative, which aims to regulate the production and use of dangerous chemicals at source, remains to be seen.（分数：50.00）(1).The regulation of marine pollution in the

24、North East Atlantic Region is based on the OSPAR Convention.（分数：5.00）(2).The fact that some tankers still have only one body-frame or have other technical defects making bigger possibility of oil spill.（分数：5.00）(3).About one-third of the pollutants entering the sea come from atmospheric inputs.（分数：5

25、.00）(4).The overgrow of algae will result in oxygen shortage In the water, which led to “creeping dead zones“.（分数：5.00）(5).In warm and mild regions, farmed fish and shellfish are also affected by POPs because they are fed fish meal.（分数：5.00）(6).As long as 2,890 km of coastline had been polluted by t

26、he oil spill of the Prestige oil tanker.（分数：5.00）(7).Off pollution caused by tanker accidents and tank washing at sea is considered as the most visible and familiar marine pollution.（分数：5.00）(8).Half of the goods transported by ships can be classified as dangerous cargoes.（分数：5.00）(9).The West Green

27、land Coast has been polluted by radioactive elements.（分数：5.00）(10).Hormone disruption in marine life is the result of accumulation of POPs.（分数：5.00）Working to Improve the Conditions of Everglades National ParkA. When many people think of Florida, images of sandy coastlines or theme park rides come t

28、o mind. But about an hour south of Miami lies a natural wilderness different from anywhere else in the United States. Everglades National Park is the largest subtropical wilderness in the country. The park is home to several rare and endangered species. It is also the third largest national park in

29、the lower forty-eight states, after Death Valley and Yellowstone. More than one million people visit the Everglades each year. B. The Everglades is considered one of the great biological wonders of the world. The expansive wetlands stretch across more than six hundred thousand hectares (公顷). It is a

30、 place where plants and animals from the Caribbean Sea share an ecosystem with native North American species. Unlike most other national parks, Everglades National Park was created to protect an ecosystem from damage. The Everglades is home to thirty-six species that are considered threatened or pro

31、tected. They include the Florida panther, the American crocodile and the West Indian manatee. In addition, more than three hundred fifty bird species and three hundred species of fresh and saltwater fish live within the park. The Everglades is also home to forty species of mammals (哺乳动物) and fifty r

32、eptile (爬行动物) species. C. Exotic plants can also be found in the Everglades. They include what is said to be the largest growth of mangrove trees in the western half of the world. Gumbo-limbo trees, known for their peeling red skin, strangler figs and royal palms are also among the area“s plant life

33、. The Everglades is also home to the country“s largest living mahogany tree. Sawgrass grows in some areas of the park. Be careful-it is very sharp, with teeth just like a saw. It can grow up to four meters tall. With about one and one-haft meters of rainfall each year, plants and trees never stop gr

34、owing in the Everglades. D. The dry, winter season is the favorite of most visitors, when insects like mosquitoes are less of a problem. The rainy season lasts from June to November. There are many ways to explore the Everglades. Visitors could see American crocodiles while hiking the Anhinga Trail.

35、 The Everglades is the only place on Earth where fresh water crocodiles and saltwater crocodiles live in the same area. Visitors using canoes or airboats are likely to see large groups of wading birds like the wood stork or great blue heron. It is even possible to see flamingos in the Everglades. Th

36、is spring, Everglades National Park launched a visitation program to what was once a highly restricted military base. Park officials are working to recover a missile base used in the 1960s. The base played a Part In the nuclear tensions between the United States and the Soviet Union. E. The governme

37、nt built the Florida base shortly after the discovery of Soviet missiles about three hundred kilometers away, on the island of Cuba. Tensions were high during the Cuban missile crisis. But missiles stored at the American base were never fired. The base was closed and all missile equipment was remove

38、d in the 1970s. Today only the buildings remain. This year, the historic area had many visitors, including former American service members who remember the missile crisis. The park hopes to offer more trips next spring, to help support the history for those who lived through it and for future genera

39、tions. F. Experts say changes to the Everglades are threatening several different kinds of wildlife. They say the threats are a result of actions the United States government began more than fifty years ago, and settlers began even earlier. The National Park Service says early colonial settlers and

40、land developers thought the Everglades had little value. The settlers had plans to remove water from the area and in the 1880s developers began digging drain canals. At the time, they did not understand the complexity of the Everglades“ ecosystem. As a result, they were not prepared for all the work

41、 and caused environmental problems. The ecosystem, however, was able to survive. G. Even larger efforts to drain the wetlands continued between 1905 and 1910. Large areas were changed to farmland. This led to increased development, with more people moving to the Ever-glades and also more visitors. M

42、ore changes came in 1948, when Congress approved the Central and South Florida Project. As part of the plan, the Army Corps of Engineers built roads, canals and water-control systems throughout South Florida. The aim of the project was to provide water and flood protection for developed areas and ag

43、riculture. Workers built a huge system of waterways and pumping stations to control the overflow of Lake Okeechobee, north of the Everglades. Today, fifty percent of south Florida“s early wetland areas no longer exist. Populations of wading birds have been reduced by ninety percent. Whole population

44、s of animals are in danger of disappearing. The endangered creatures include the manatee, the Miami blackhead snake, the wood stork and the Florida panther. H. In recent years, environmental experts have learned about the damage to the Everglades. They say the natural balance of plants and animals h

45、as been destroyed. Recently, the Obama administration promised three hundred sixty million dollars to pay for Everglades restoration this year. The administration is also asking that Congress approve an additional two hundred seventy-eight million dollars for next year. The money will help to suppor

46、t projects approved by the government nine years ago. The projects include improving wetlands in the Picayune Strand in Southwest Florida and repairs to Lake Okeechobee“s dam. Until now, the state of Florida has spent the most money on the project. I. Another threat biologists have been battling for

47、 years in the Everglades is the area“s population of Burmese pythons (large snakes). Officials believe there are as many as one hundred fifty thousand of these large snakes in the Everglades. But the snakes are a foreign species, native to Southeast Asia. Owners of pythons left their unwanted snakes

48、 in the Everglades years ago. Biologists say adult pythons are able to eat small deer and bobcats. When pythons are found in the Everglades, they are often killed. Scientists are now experimenting with other ways to remove the snakes, including trapping methods and offering payments to hunters. The

49、future of the Everglades is not clear. However, efforts to protect the area are continuing so that people from all over the world may continue visiting this biological treasure.（分数：50.00）(1).Efforts to protect the area would be continued though the future of Everglades is still unknown.（分数：5.00）(2).In order to provide water and flood protection for developed areas and agriculture, the Congress approved the Central and South Florida Project.（分数：5.00）(3).The Soviet Union placed missiles on the island of Cuba during the Cuban missile crisis.（分数：5.00）(4).With an ecosystem of plants and animals bo