大学英语四级模拟试题

2010年英语四级模拟及试题及答（2）Part I Writing (30 minutes)Directions: In this part you are allowed 30 minutes to write an essay entitled The Heavy Burden of Study. You should write at least 120 words according to the outline given below:1现在学生的学习负担越来越重2学习负担越来越重的原因 3应该如何解决这个问题The Heavy Burden of StudyPart 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:For questions 1 7, mark Y (for YES)if the statement agrees with the information given in the passage;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.For questions 8 10, complete the sentences with the information given in the passage.The Hydrogen EconomyIt 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 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 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 fuel economyWhile 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 gasNitrogen oxides, the main source of urban smogUnburned 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 warming The 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 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 but to pay the higher price.Advantages of the hydrogen economyThe 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, 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. 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 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 significant, 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 natural 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 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 consisting 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 perverse (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 hydrogen 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 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 United States comes from coal or natural gas. All of that generating capacity will have to be 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 powerHydroelectric damsSolar cellsWind turbinesGeothermal powerWave and tidal powerCo-generationHow 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 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 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 develop quickly; that sort of standardization is unlikely to happen rapidly, if history is any guide.Prospects for the futureYou 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 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 major improvements over the internal combustion engine:They are about twice as efficient.They can significantly reduce air pollution in cities. 1. The passage gives a general description of the benefits and potential problems of a hydrogen economy.2. An oil spill can pose a big problem to the environment.3. Compared with other major industrialized countries, the United States depends more heavily on oil import.4. Even if you have electricity and water, you still cannot produce hydrogen everywhere.5. In the United States, most of the electricity is generated from coal or natural gas.6. We must derive hydrogen from renewable sources with a view to a pure hydrogen economy.7. So far, there seems to be no solution in sight as to how the hydrogen can be stored.8. Possible sources for the hydrogen are both electrolysis of water and _.9. If the storage problem is _ and _, a network of hydrogen stations and the transportation infrastructure will have to develop around it.10. Concerning the future of the hydrogen economy, the most obvious step we will take is _. Part IVReading Comprehension (Reading in Depth) (25 minutes)Section ADirections: In this section, there is a passage with 10 blanks. You are required to select the word for each blank from a list of choices given in a word bank following the passage. Read the passage through carefully before making your choices. Each choice in the bank is identified by a letter. Please mark the corresponding letter for each item on the answer sheet with a single line through the centre. You may not use any of the words in the bank more than once.Questions 47 to 56 are based on the following passage. Few people question the wisdom of dieting. After all, we reason, the worst that can happen is that well 47 the weight weve lost then we can simply go on a diet again. But some new research suggests there is a risk: yo-yo dieting may seriously 48 the bodys weight-control system. The more diets you go on，the harder it may become to lose weight. Ever worse，new _49_ indicates that repeated 50 of losing and gaining weight may raise the risk of heart problem. This last possibility is especially 51 . As part of a 25-year study that 52 1959 men, researchers reported that the men showing large up-and-down weight changes had twice the risk of heart disease as those with only small changes in weight. One study shows people who lost ten percent of their body weight had about 20 percent 53 in risk of heart disease but people who gained from 150 to 185 pounds, and back to 150 again, could leave you with a higher heart-disease risk than you started with.None of this means that dieting is 54 or foolish. For those who are 20 percent or more overweight，there are good reasons to reduce: successful weight loss can 55 blood pressure, help control blood sugar in diabetics and enable people to feel better about themselves. But the new research does suggest that dieting must be taken 56 by people at any weight.A) conceptI) seriouslyB) reductionJ) monitoredC) theoryK) predictD) regainL) distortE) disturbingM) accurateF) ineffectiveN) lowerG) overallO) cyclesH) evidenceSections BDirections: There are 2 passages in this section. Each passage is followed by some questions or unfinished statements. For each of them there are four choices marked A), B), C) and D). You should decide on the best choice and mark the corresponding letter on the Answer Sheet with a single line through the centre. Passage OneQuestions 57 to 61 are based on the following passage. Humanity uses a little less than half the water available worldwide. Yet occurrences of shortages and droughts (干旱) are causing famine and distress in some areas, and industrial and agricultural by-products are polluting water supplies. Since the worlds population is expected to double in the next 50 years, many experts think we are on the edge of a widespread water crisis. But that doesnt have to be the outcome. Water shortages do not have to trouble the world if we start valuing water more than we have in the past. Just as we began to appreciate petroleum more after the 1970s oil crises, today we must start looking at water from a fresh economic perspective. We can no longer afford to consider water a virtually free resource of which we can use as much as we like in any way we want.Instead, for all uses except the domestic demand of the poor, governments should price water to reflect its actual value. This means charging a fee for the water itself as well as for the supply costs.Governments should also protect this resource by providing water in more economically and environmentally sound ways. For example, often the cheapest way to provide irrigation (灌溉) water in the dry tropics is through small-scale projects, such as gathering rainfall in depressions (凹地) and pumping it to nearby cropland. No matter what steps governments take to provide water more efficiently, they must change their institutional and legal approaches to water use. Rather than spread control among hundreds or even thousands of local, regional, and national agencies that watch various aspects of water use, countries should set up central authorities to coordinate water policy.57. What is the real cause of the potential water crisis?A) Only half of the worlds water can be used.B) The world population is increasing faster and faster.C) Half of the worlds water resources have been seriously polluted.D) Humanity has not placed sufficient value on water resources.58. As indicated in the passage, the water problem _.A) is already serious in certain parts of the worldB) has been exaggerated by some experts in the fieldC) poses a challenge to the technology of building reservoirsD) is underestimated by government organizations at different levels59. According to the author, the water price should _.A) be reduced to the minimumB) stimulate domestic demandC) correspond to its real valueD) take into account the occurrences of droughts60. The author says that in some hot and dry areas it is advisable to _.A) build big lakes to store waterB) construct big pumping stationsC) build small and cheap irrigation systemD) channel water from nearby rivers to cropland61. In order to raise the efficiency of the water supply, measures should be taken to _.A.guarantee full protection of the environmentB.centralize the management of water resourcesC.increase the sense of responsibility of agencies at all levelsD.encourage local and regional control of water resourcesPassage Two Questions 62 to 66 are based on the following passage. Most episodes of absent-mindedness forgetting where you left something or wondering why you just entered a room are caused by a simple lack of attention, says Schacter. “Youre supposed to remember something, but you havent encoded it deeply.”Encoding, Schacter explains, is a special way of paying attention to an event that has a major impact on recalling it later. Failure to encode properly can create annoying situations. If you put your mobile phone in a pocket, for example, and dont pay attention to what you did because youre involved in a conversation, youll probably forget that the phone is in the jacket now hanging in your wardrobe (衣柜). “Your memory itself isnt failing you,” says Schacter. “Rather, you didnt give your memory system the information it needed.”Lack of interest can also lead to absent-mindedness. “A man who can recite sports statistics from 30 years ago,” says Zelinski, “may not member to drop a letter in the mailbox.” Women have slightly better memories than men, possibly because they pay more attention to their environment, and memory relies on just that.Visual cues can help prevent absent-mindedness, says Schacter. “But be sure the cue is clear and available,” he cautions. If you want to remember to take a medication (药物) with lunch, put the pill bottle on the kitchen table dont leave it in the medicine chest and write yourself a note that you keep in a pocket.Another common episode of absent-mindedness: walking into a room and wondering why youre there. Most likely, you were thinking about something else. “Everyone does this from time to time,” says Zelinski. The best thing to do is to return to where you were before entering the room, and youll likely remember.62. Why does the author think that encoding properly is very important? A) It expands our memory capacity considerably.B) It helps us understand our memory system better.C) It slows down the process of losing our memory.D) It enables us to recall something from our memory63. One possible reason why women have better memories than men is that _.A) they are more interested in whats happening around themB) they have an unusual power of focusing their attentionC) they are more reliant on the environmentD) they have a wider range of interests64. A note in the pocket can hardly serve as a reminder because _.A) it might get mixed up with other thingsC) it will easily get lostB) its not clear enough for you to readD) its out of your sight65. What do we learn from the last paragraph?A) Repetition helps improve our memory.B) Memory depends to a certain extent on the environment.C) If we focus our attention on one thing, we might forget another.D) If we keep forgetting things, wed better return to where we were.66. What is the passage mainly about?A) The causes of absent-mindedness.B) A way of encoding and recalling.C) The process