1、大学英语四级模拟试卷 520及答案与解析 一、 Part I Writing (30 minutes) 1 For this part, you are allowed 30 minutes to write a letter to the president of your university. You should write at feast 120 words based on the outline given below in Chinese: 1. 学校教学应该注重学生学习方法的培 养 2. 学校应该丰富学生的校园生活 二、 Part II Reading Comprehens
2、ion (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 passage; N (for NO) if the state
3、ment contradicts the information given in the passage; NG (for NOT GIVEN) if the information is not given in the passage. 1 THE HYDROGEN ECONOMY It seems-like every day there is a new announcement in the news about automobiles powered by fuel cells. The promises are great, since fuel cells have the
4、potential to very quickly double the efficiency of cars while significantly reducing air pollution. At the same time, there have been news stories for decades about the problems associated With petroleum. Everything from oil spills to ozone(臭氧 ) alerts to global warming gets blamed on our dependence
5、 on fossil(化石 ) fuels. These two forces are leading the world toward what is broadly known as the hydrogen economy. If the predictions are true, over the next several decades we will all begin to see an amazing shift away from the fossil fuel economy we have today toward a much cleaner hydrogen futu
6、re. Problems with the fossil fuel economy While fossil fuels have played an important role in getting society to the point it is at today, there are four big problems that fossil fuels create: Air pollution-When cars burn gasoline, the internal combustion engine also produces: Carbon monoxide, a poi
7、sonous gas Nitrogen oxides, the main source of urban smog Unburned hydrocarbons, the main source of urban ozone Environmental pollution-The process of transporting and storing oil has a big impact on the environment whenever something goes wrong. An oil spill, pipeline explosion or well fire can cre
8、ate a huge mess. Global warmingThe carbon dioxide coming out of every cars tailpipe is a greenhouse gas that is slowly raising the temperature of the planet. The ultimate effects are unknown, but it is a strong possibility that, eventually, there will be dramatic climate changes that affect everyone
9、 on the planet. Dependence-The United States, and most other Countries, cannot produce enough oil to meet demand, so they import it from oil-rich countries. That creates an economic dependence. When Middle East oil producers decide to raise the price of oil, the rest of the world has little choice b
10、ut to pay the higher price. Advantages of the hydrogen economy The hydrogen economy promises to eliminate all of the problems that the fossil fuel economy creates. Therefore, the advantages of the hydrogen economy include: The elimination of pollution caused by fossil fuels-When hydrogen is used in
11、a fuel cell to create power, it is a completely clean technology. The only byproduct is water. There are also no environmental dangers like oil spills to worry about with hydrogen. The elimination of greenhouse gases-If the hydrogen comes from the electrolysis of water, then hydrogen adds no greenho
12、use gases to the environment. There is a perfect cycle-electrolysis produces hydrogen from water, and the hydrogen recombines with oxygen to create water and power in a fuel cell. The elimination of economic dependence-The elimination of oil means no dependence on the Middle East and its oil reserve
13、s. Distributed production-Hydrogen can be produced anywhere that you have electricity and water. People can even produce it in their homes with relatively simple technology. The problems with the fossil fuel economy are so great, and the environmental advantages of the hydrogen economy so significan
14、t, that the push toward the hydrogen economy is very strong. Technological Hurdles(障碍 ) The big question with the hydrogen economy is, “Where does the hydrogen come from?“ After that comes the question of transporting, distributing and storing hydrogen. Hydrogen tends to be large and tricky in its n
15、atural gaseous form. Once both of these questions are answered in an economical way, the hydrogen economy will be in place. Where does the hydrogen come from? There are two possible sources for the hydrogen: Electrolysis of water-Using electricity, it is easy to split water molecules to create pure
16、hydrogen and oxygen. One big advantage of this process is that you can do it anywhere. For example, you could have a box in your garage producing hydrogen from tap water, and you could fuel your car with that hydrogen. Reforming fossil fuels-Oil and natural, gas contain hydrocarbons-molecules consis
17、ting of hydrogen and carbon. Using a device called a fuel processor or a reformer, you can split the hydrogen off the carbon in a hydrocarbon relatively easily and then use the hydrogen. You discard the leftover carbon to the atmosphere as carbon dioxide. The second option is, of course, slightly pe
18、rverse(不正当的 ). You are using fossil fuel as the source of hydrogen for the hydrogen economy. This approach reduces air pollution, but it doesnt solve either the greenhouse gas problem or the dependence problem. However, it may be a good temporary step to take during the transition(转变 ) to the hydrog
19、en economy. The interesting thing about the first option is that it is the core of the real hydrogen economy. To have a pure hydrogen economy, the hydrogen must be derived from renewable sources rather than fossil fuels so that we stop releasing carbon into the atmosphere. Having enough electricity
20、to separate hydrogen from water, and generating that electricity without using fossil fuels, will be the biggest change that we see in creating the hydrogen economy. Where will the electricity for the electrolysis of water come from? Currently, about 68 percent of the electricity produced in the Uni
21、ted States comes from coal or natural gas. All of that generating capacity will have to he replaced by renewable sources in the hydrogen economy. Right now there are several different ways to create electricity that do not use fossil fuels: Nuclear power Hydroelectric dams Solar cells Wind turbines
22、Geothermal power Wave and tidal power Co-generation How do you store and transport the hydrogen? Hydrogen is a large gas of its kind, and it is not nearly as easy to work with as gasoline. Compressing the gas requires energy, and compressed hydrogen contains far less energy than the same volume of g
23、asoline. However, solutions to the hydrogen storage problem are surfacing. For example, hydrogen can be stored in a solid form in a chemical called sodium borohydride. Once the storage problem is solved and standardized, then a network of hydrogen stations and the transportation infrastructure will
24、have to develop around it. The main barrier to this might be the technological sorting-out process. Stations will not develop quickly until there is a storage technology that clearly dominates the marketplace. For instance, if all hydrogen-powered cars from all manufacturers used sodium borohydride,
25、 then a station network could develop quickly; that sort of standardization is unlikely to happen rapidly, if history is any guide. Prospects for the future You will hear more and more about the hydrogen economy in the news in the Coming months, because the drumbeat is growing louder. The environmen
26、tal problems of the fossil fuel economy are combining with breakthroughs(突破 ) in fuel-cell technology, and the pairing will allow us to take the first steps, The most obvious step we will see is the marketing of fuel-cell-powered vehicles. Although they will be powered initially by gasoline and refo
27、rmers, fuel cells represent two major improvements over the internal combustion engine: They are about twice as efficient. They can significantly reduce air pollution in cities. 2 The passage gives a general description of the benefits and potential problems of a hydrogen economy. （ A） Y （ B） N （ C）
28、 NG 3 An oil spill can pose a big problem to the environment. （ A） Y （ B） N （ C） NG 4 Compared with other major industrialized countries, the United States depends more heavily on oil import. （ A） Y （ B） N （ C） NG 5 Even if you have electricity and water, you still cannot produce hydrogen everywhere
29、. （ A） Y （ B） N （ C） NG 6 In the United States, most of the electricity is generated from coal or natural gas. （ A） Y （ B） N （ C） NG 7 We must derive hydrogen from renewable sources with a view to a pure hydrogen economy. （ A） Y （ B） N （ C） NG 8 So far, there seems to be no solution in sight as to h
30、ow the hydrogen can be stored. （ A） Y （ B） N （ C） NG 9 Possible sources for the hydrogen are both electrolysis of water and _. 10 If the storage problem is _ and _, a network of hydrogen stations and the transportation infrastructure will have to develop around it. 11 Concerning the future of the hy
31、drogen economy, the most obvious step we will take is _. Section A Directions: In this section, you will hear 8 short conversations and 2 long conversations. At the end of each conversation, one or more questions will be asked about what was said. Both the conversation and the questions will be spok
32、en only once. After each question there will be a pause. During the pause, you must read the four choices marked A, B, C and D, and decide which is the best answer. （ A） He doesnt want the woman to give him money. （ B） He doesnt remember how much the groceries cost. （ C） Picking up groceries for the
33、 woman is even worth nothing. （ D） He forgot about the concert tickets the woman paid for him last week. （ A） Wait for the video to come out. （ B） Never see it since its not his type. （ C） See it later when he is not so busy. （ D） Not see it since he has seen it before. （ A） No one was interested in
34、 discussing politics. （ B） People avoid discussing politics. （ C） The woman is not being serious. （ D） Politics is a sensitive topic. （ A） His flight arrived late. （ B） His flight took three hours. （ C） Mary had a long drive to the airport. （ D） Mary had trouble finding the airport. （ A） She intends
35、 to visit her friend in Texas. （ B） She sometimes travels abroad for her job. （ C） Her friend has never been to Texas before. （ D） She hasnt spoken to her friend for a long time. （ A） She needs to review her notes. （ B） She has no free time next weekend. （ C） The article is so boring, so shell write
36、 a review next weekend. （ D） She wants to finish quickly so she can relax the following week. （ A） In a travel agency. （ B） At the reception desk. （ C） In a doctors office. （ D） In a drugstore. （ A） She wants to hand in her report early. （ B） She is sorry the man has to cancel the plan. （ C） She wou
37、ld like to go to the symphony with the man. （ D） She cant go to the symphony because of her unfinished report. （ A） A standard unit for measuring weight. （ B） How to care for precious metals. （ C） The value of precious metals. （ D） Using the metric system. （ A） To measure amounts of rainfall. （ B） T
38、o cheek the accuracy of scales. （ C） To observe changes in the atmosphere. （ D） To calculate the density of other metals. （ A） It is too high for such a light weight. （ B） It is difficult to judge the value of such an object. （ C） It is a small amount to pay for so much precious metal. （ D） It is re
39、asonable for an object with such an important function. （ A） The benefits of strong business competition. （ B） A proposal to lower the cost of production. （ C） Complaints about the expense of modernization. （ D） Suggestions concerning new business strategies. （ A） It cost much more than its worth. （
40、 B） It should be brought up-to-date. （ C） It calls for immediate repairs. （ D） It can still be used for a long time. （ A） The personnel manager should be fired for inefficiency. （ B） A few engineers should be employed to modernize the factory. （ C） The entire staff should be retrained. （ D） Better-e
41、ducated employees should be promoted. （ A） Their competitors have long been advertising on TV. （ B） TV commercials are less expensive. （ C） Advertising in newspapers alone is not sufficient. （ D） TV commercials attract more investments. Section B Directions: In this section, you will hear 3 short pa
42、ssages. At the end of each passage, you will hear some questions. Both the passage and the questions will be spoken only once. After you hear a question, you must choose the best answer from the four choices marked A, B, C and D. （ A） Rich enough and old enough. （ B） Strong and under the age of 70.
43、（ C） Healthy and over the age of 17. （ D） Having been trained and passed the driving test. （ A） More traffic jams. （ B） More car accidents. （ C） More damaged roads. （ D） More drunk drivers. （ A） The roads are too crowded to drive. （ B） Its difficult to catch a bus or a train. （ C） They are too young
44、 or too old to drive. （ D） Train and bus services are becoming poorer. （ A） Resident advice. （ B） Summer vacation. （ C） The housing office. （ D） Check out procedures. （ A） Call the housing office. （ B） Repair holes in room walls. （ C） Remove personal property. （ D） Register for summer school. （ A） S
45、tudents summer addresses. （ B） Any damage to their rooms. （ C） When they plan to come back. （ D） Comments on the housing office. （ A） The material to be tested that day. （ B） The history of the slide library. （ C） The use of slides in the course. （ D） The outline of the course. （ A） The beginning of
46、 the semester. （ B） Just before the first weekly exam. （ C） Halfway through the course. （ D） Just before the final exam. （ A） Those who have visual disabilities. （ B） Those who intend to become artists. （ C） Those who have no interest in painting. （ D） Those who have never taken art history before.
47、（ A） Reasons for Peoples Sleeping. （ B） Four Stages of Sleep. （ C） Reasons for sleepwalking. （ D） A Sleep Experiment. Section C Directions: In this section, you will hear a passage three times. When the passage is read for the first time, you should listen carefully for its general idea. When the pa
48、ssage is read for the second time, you are required to fill in the blanks numbered from 36 to 43 with the exact words you have just heard. For blanks numbered from 44 to 46 you are required to fill in the missing information. For these blanks, you can either use the exact words you have just heard o
49、r write down the 36 After retiring from 30 years of teaching, Ethbell Pepper could easily have decided to sit back and【 B1】 _and enjoy a peaceful【 B2】 _. But that kind of life is not for Ethbell pepper. “I just wanted to do something【 B3】 _. If you are going to【 B4】 _in life, do it. Dont just sit down and look out the window,“ said she. At 68, she decided to become one of the【 B5】 _participants in a program at the University of California; The program offers【 B6
