大学英语四级257及答案解析.doc

1、大学英语四级 257 及答案解析(总分：746.56，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 thirty minutes to write a composition about the building of a new supermarket. You should write at least 120 words according to the guidelines given below in Chinese: 假设你居住的小区(neighborhood)要

2、建一家新的超市(supermarket)，居委会征求大家意见。你是否支持这项计划并给出你的原因。 （分数：30.00）_二、Reading Comprehensio(总题数：1，分数：71.00)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 potential to very quickly

3、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 on fossil(化石) fuels. These

4、 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 future. Problems with the fossil

5、 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 poisonous gas Nitrogen oxides,

6、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 create a huge mess. Global warm

7、ingThe 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 on the planet. Dependence-T

8、he 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 but to pay the higher price.

9、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 a fuel cell to create power,

10、 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 greenhouse gases to the environment

11、 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 reserves. Distributed production-Hy

12、drogen 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 significant, that the push toward the

13、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 natural gaseous form. Once bot

14、h 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 hydrogen and oxygen. One big

15、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 consisting of hydrogen and carbon.

16、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 perverse(不正当的). You are using f

17、ossil 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 hydrogen economy. The interesting thi

18、ng 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 to separate hydrogen from water

19、 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 United States comes from coal or n

20、atural 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 Geothermal power Wave and tidal

21、 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 gasoline. However, solutions to

22、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 have to develop around it. The

23、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, then a station network could d

24、evelop 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 environmental problems of the fossil fuel

25、 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 reformers, fuel cells represent two

26、major improvements over the internal combustion engine: They are about twice as efficient. They can significantly reduce air pollution in cities. （分数：71.00）(1).The passage gives a general description of the benefits and potential problems of a hydrogen economy. （分数：7.10）A.YB.NC.NG(2).An oil spill ca

27、n pose a big problem to the environment. （分数：7.10）A.YB.NC.NG(3).Compared with other major industrialized countries, the United States depends more heavily on oil import. （分数：7.10）A.YB.NC.NG(4).Even if you have electricity and water, you still cannot produce hydrogen everywhere. （分数：7.10）A.YB.NC.NG(5

28、).In the United States, most of the electricity is generated from coal or natural gas. （分数：7.10）A.YB.NC.NG(6).We must derive hydrogen from renewable sources with a view to a pure hydrogen economy. （分数：7.10）A.YB.NC.NG(7).So far, there seems to be no solution in sight as to how the hydrogen can be sto

29、red. （分数：7.10）A.YB.NC.NG(8).Possible sources for the hydrogen are both electrolysis of water and _. （分数：7.10）_(9).If the storage problem is _ and _, a network of hydrogen stations and the transportation infrastructure will have to develop around it. （分数：7.10）_(10).Concerning the future of the hydrog

30、en economy, the most obvious step we will take is _. （分数：7.10）_三、Listening Comprehens(总题数：1，分数：15.00)A.He is an American.B.Not mentioned.C.He is a Chinese.D.He is a Japanese.A.Her hometown has changed a lot.B.She hasnt gone to any place.C.To her surprise, the man hasnt seen her for a long time.D.She

31、 is no longer the woman she was three years ago.A.The woman heard Ann was working in a hospital.B.The man saw Ann killed in an accident.C.Ann survived an accident.D.Ann was killed in an accident.A.11:20.B.9:20.C.Around 10.D.Around 13.A.It is neither cold nor hot in his hometown.B.It is very hot in h

32、is hometown.C.Its quite cold in his hometown.D.Its so warm here.A.The lecture is excellent.B.The lecture is very bad.C.She is somewhat interested in the lecture.D.She is astonished by the lecture.A.Because Tom wasnt at home.B.Because the man didnt get the right telephone number.C.Because Tom was too

33、 busy to come.D.Because there was something wrong with Toms phone.A.The woman suffered from her stomach trouble during the trip.B.The woman ate too much during the trip.C.The woman suffered from seasickness during the trip.D.The woman was frightened by the big waves.四、Section B(总题数：2，分数：10.00)A.He c

34、ant find his office key.B.He has misplaced some exams.C.Hes unable to talk.D.He doesnt like his classroom.A.Mark the latest homework assignment.B.Put a cancellation notice on the classroom door.C.Make an appointment with the doctor.D.Return some exams to his students.A.Teach Dons class while hes abs

35、ent.B.Give Professor Webster the key to Dons office.C.Leave a message on the board in Dons classroom.D.Bring Don the homework that was due today.A.Put the homework on Dons desk.B.Leave the master key for Don.C.Give Dons students the next assignment.D.Call Don at the end of the afternoon.A.She bought

36、 a mug.B.She fell while walking home from work.C.She was robbed.D.She lost her left shoe carelessly on her way home.A.A woman with a beard.B.A woman.C.A man.D.Not mentioned.A.On the street.B.In a store.C.On the playground.D.In the park.A.Trial-producing smaller cars to replace the bigger ones that a

37、re used today.B.Mass-producing some kinds of cars for tomorrow.C.Trying to make some new style vehicles that would be faster and safer than the ones used today.D.Designing some cars that would have many advantages over the ones used today.A.They are pretty, safe and cheap.B.They are cheap and durabl

38、e.C.They are safe, cheap and clean.D.They are powerful, beautiful and easy to drive.A.Both the big and small cars have some defects.B.The speaker is fully optimistic that the new cars will replace the cars in use today.C.The number of cars in use today should be reduced because of the pollution in c

39、ities.D.Gasoline is a pollutant, so other kinds of fuel should be found to replace it.A.Description.B.Argumentation.C.Joke.D.Exposition.A.To make a journey.B.To attend a meeting.C.To purchase something.D.To meet his wife.A.The scientist is too timid to exchange seats.B.The broken seat distresses the

40、 scientists liver.C.Its the first time the scientist be ashen and distraught.D.No one sits in the seat facing the scientist.A.Inflexible.B.Diligent.C.Bulky.D.Bright.A.Tiger.B.Bear.C.Fox.D.Wolf.A.He ran through the forest quickly.B.He stopped dead and was too scared to do anything.C.He fired his gun

41、at the bear.D.He lost his balance and fell down the hill.A.He had a broken leg.B.He had a broken arm.C.He was too scared to move.D.He was too weak to move.A.He would leave the bear alone.B.He would pray for the bear.C.He would kill the bear.D.None of the above.六、Section C(总题数：1，分数：10.00)A northern c

42、old spell gripped much of northern and eastern China yesterday, as local authorities issued terrible weather warnings and launched (36) 1plans to ensure safe transportation in the snow. The cold front, which brought snow showers mainly to Henan, Anhui, Shaanxi and Gansu provinces, (37) 2Beijing, Tia

43、njin, Hebei and Liaoning provinces, putting pressure on the post-Spring-Festival travel (38) 3The bad weather has caused (39) 4on roads, trains and airports. Several highways surrounding Beijing were closed yesterday. Delays and (40) 5 of flights at several airports meant many (41) 6were unable to r

44、eturn to work after the week-long holiday. “At least four flights of the China Eastern Airlines were (42) 7because of the snow,“ said a (43) 8with the airport in Lanzhou, capital of Northwest Chinas Gansu Province. In Shenyang, capital of Northeast Chinas Liaoning Province, (44) 9. No major incident

45、s of stranded passengers at railway stations were reported. (45) 10. Rail conditions in Zhengzhou, capital of Central Chinas Henan Province, have returned to normal after the station launched an plan on Sunday in response to the heavy snow, and evacuated tens of thousands of passengers. (46) 11. The

46、 seas in the east and south may also be hit with high winds. （分数：10.00）填空项 1:_填空项 1:_填空项 1:_填空项 1:_填空项 1:_填空项 1:_填空项 1:_填空项 1:_填空项 1:_填空项 1:_填空项 1:_七、Reading Comprehensio(总题数：2，分数：355.00)On 10 September 2001, Charles Ingram, an officer in the British army, became a millionaire but only for a few hou

47、rs. That night, he appeared on the UKs “Who wants to be a Millionaire“ quiz show. Contestants on this show must answer 15 questions correctly, getting larger sums of money each time. If they answer all the questions, they walk away with 1 million. Charles Ingram won his million. But then the program makers decided he had cheated. Contestants have to choose one correct answer from four given to every question. Playing back the tape of the show, they heard loud coughs coming from the audience whenever the correct answer was mentioned. Charles Ingram would then cho