[外语类试卷]大学英语四级模拟试卷184及答案与解析.doc
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1、大学英语四级模拟试卷 184及答案与解析 一、 Part I Writing (30 minutes) 1 For this part, you are allowed thirty minutes to write a composition on the topic On the Olympic Games. You should write at least 120 following the outline given below in Chinese: 1.奥运是当今世界上最令人振奋的事 件之一。 2.奥运也给举办国的经济发展带来了机遇。 3.我国 (北京 )应该如何为奥运做准备。
2、二、 Part II Reading Comprehension (Skimming and Scanning) (15 minutes) Directions: In this part, you will have 15 minutes to go over the passage quickly and answer the questions attached to the passage. For questions 1-7, mark: Y (for YES) if the statement agrees with the information given in the pas
3、sage; N (for NO) if the statement contradicts the information given in the passage; NG (for NOT GIVEN) if the information is not given in the passage. 1 ACID RAIN: Whats the Solution? One of the wildest regions in the U.S., far from civilization, is the Adirondack area of northern New York State. Fo
4、r years this isolated spot has had the reputation of being one of best fishing spots in the U.S. As a boy 30 years ago, Bill Marleau first through the Adirondack wilderness near his small cabin on Woods Lake. Thousands of sportsmen have stayed at his fathers lodge nearby. But now Bills 134 hectares
5、(335 acres) of lakefront land have only scenic value. Gone are those huge trout that used to swim in the turbulent, nutrientrich water a short distance from his doorstep. Gone from the cool nights are the sounds of thousands of frogs and toads. And gone are the birds that once fed on those water cre
6、atures. Occasionally Bill sees a lone fisherman fruitlessly cast his bait into the empty waters of old lake. “I just dont have the heart to tell,“ he said. “This old lakes dead. It was killed years ago by acid rain.“ What is acid rain? Acid rain is a popular term for precipitation in the form of rai
7、n, sleet, snow or hail that is more acidic than normal. Acid rain is produced when atmospheric moisture combines with pollutants from power plants, factories and automobiles. When fossil fuels such as coal and oil are burned, sulfur dioxide and nitrogen dioxide are produced. These two gases react wi
8、th the water and oxygen in the atmosphere to form droplets of weak sulfur and nitric acid. Carried by prevailing winds and weather conditions, clouds containing these droplets travel hundreds, sometimes thousands, of kilometers from the source of the pollutants. Recently scientists found that acid r
9、ain now affects huge areas of the North Hemisphere. Power plants and factories in the heavily industrialized regions of Ohio and Indiana are believed to be the source of the acid rain that killed Woods Lake along with hundreds of others in New York State and eastern Canada. Acid haze over Alaska is
10、believed to come all the way from Japan. And precipitation as acid as vinegar that falls on Scotland and Scandinavia probably originates in England. How Acidity Is Measured Scientists measure the acidity of rain in pH units. A pH scale from 0 to 14 is used. Depending upon its chemical composition, a
11、 solution is either acidic, alkaline (basic), or neutral. Distilled water, which has a pH of 7, is neutral. Substance with pH values less than 7 are acidic, while those over 7 are alkaline. Normal rain water with a pH of 5.6 is slightly acidic. But after reacting with industrial pollutants, particul
12、arly sulfur dioxide, the pH of rain quickly drops. When acid rain falls to Earth, much of it ends up in lakes and ponds. In addition to failing directly into a lake, acid rains runs off land into streams and rivers that eventually flow into lakes and ponds. Once acid rain gets into them, its effects
13、 can be deadly. Studies started in 1975 in the Adirondacks indicate that salamanders and frogs are the first to die when the pH is lowered. Normally the pH of a lake is 8,0 slightly alkaline. When the pH drops to 7, the eggs of salamanders and frogs fail to hatch. At pH 6.6 snails begin to die. Bact
14、eria that decompose leaf matter die too, and the leaf matter collects on the lake bottom. As the acidity continues to drop, ail the major food chains in the lake become affected. In time all the fish die. Eventually primitive, oxygenconsuming plants nearly choke out all other aquatic greenery. Algae
15、 and fungal growth that thrive in an acidic environment move in and cover the entire bottom of the now destroyed lake. Looking like blue vinegar, the lake is now an entirely changed ecosystem. It contains no life expect the fungal and algal growth and a few surfacedwelling water bugs. Acid rain also
16、 affects plants on land. The effects of acid rain on terrestrial vegetation are not as well documented or as clearly understood as its effects on lake. Experiments by Ellis B. Cowling of North Carolina State University, however, indicate that acid rain destroys the natural waxy coating on tree leave
17、s and fruits. This destruction makes the plants more susceptible to disease. Acid Rain Increasing The acid rain problem seems to be getting worse. According to the Environmental Protection Agency, the amount of sulfur dioxide from power plants, autos, and factories is four times greater than it was
18、25 years ago. And federal airpollution regulations dont seem to be helping as much as had been expected. One problem is that the Clean Air Act of 1977 established air pollution standard based on measurements made at ground level. Environmentalists claim that this action has encouraged polluters to s
19、pread airborne pollutants at higher elevation instead of eliminating them altogether. Tall smokestacks, often more than 100 stories tall, now spread sulfur dioxide close to watercarrying clouds. Power company officials stress, however, that the tall stacks significantly reduce air pollution in areas
20、 near the power plants. And the officials also point to cleanup currently underway in the industry to reduce the amount of pollutants. New, cleanerburning furnaces have been installed in recently constructed power plants. Scrubbers are also available that can be installed on industrial and power pla
21、nt smokestacks. The scrubbers can remove up to 85 percent of the sulfur such as lowsulfur, liquid coal. What can be done about lakes that are already acidic? Acidity can be reduced by dropping tons of lime (an alkaline substance) into the lake water. However, this solution is very expensive. Less op
22、timistic scientists are trying to breed acidtolerant fish. These, however measures at best. The solution to acid rain can only come about cooperation between industry, government, and scientists. 2 The Adirondack area of northern New York State has changed a lot by acid rain. ( A) Y ( B) N ( C) NG 3
23、 Acid rain is produced when atmospheric moisture combines with pollutants from paper mill (造纸厂 ) , factories and automobiles. ( A) Y ( B) N ( C) NG 4 Acid rain means the precipitation in the form of rain, snow or hail which is more acidic than normal. ( A) Y ( B) N ( C) NG 5 Substances with pH value
24、s less than 7 are alkaline. ( A) Y ( B) N ( C) NG 6 When the acidity insists on dropping, many creatures in the lakes and ponds will become affected. ( A) Y ( B) N ( C) NG 7 The acid rain destroys the protection on tree leaves, which makes the plants more vulnerable to disease. ( A) Y ( B) N ( C) NG
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- 外语类 试卷 大学 英语四 模拟 184 答案 解析 DOC
