1、大学英语四级模拟试卷 971及答案与解析 一、 Part I Writing (30 minutes) 1 For this part, you are allowed 30 minutes to write a short passage entitled Free Admission to Museums. You should write at least 120 words following the outline given below. 1、越来越多的博物馆免费对外开放的目的是什么； 2、也会带来一些问题； 3、你的看法。 Free Admission to Museums _
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 p
3、assage; 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 Nuclear power plants provide about 17 percent of the worlds electricity. Some countries depend more on nuclear power for electricity than others.
4、 In France, for instance, about 75 percent of the electricity is generated from nuclear power, according to the International Atomic Energy Agency. In the United States, nuclear power supplies about 15 percent of the electricity overall, but some states get more power from nuclear plants than others
5、. There are more than 400 nuclear power plants around the world, with more than 100 in the United States. Have you ever wondered how a nuclear power plant works or how safe nuclear power is? In this article, we will examine how a nuclear reactor and a power plant work. Uranium Uranium is a fairly co
6、mmon element on Earth, which was taken into the planet during the planets formation. Uranium is originally formed in stars. Old stars exploded, and the dust from these shattered stars aggregated together to form our planet. Uranium-238 (U-238) has an extremely long life (4.5 billion years), and ther
7、efore is still present in fairly large quantities. U-238 makes up 99 percent of the uranium on the planet. U-235 makes up about 0.7 percent of the remaining uranium found naturally, while U-234 is even rarer and is formed by the decay of U-238. Nuclear Fission (裂变 ) A nuclear fission happens when a
8、uranium-235 nucleus with a neutron captures another neutron. The nucleus then splits into two lighter atoms and throws off two or three new neutrons (the number of ejected neutrons depends on how the U-235 atom happens to split). The two new atoms then produce gamma radiation as they settle into the
9、ir new states. There are three things about this induced fission process that make it especially interesting: The probability of a U-235 atom capturing a neutron as it passes by is fairly high. In a reactor working properly (known as the critical state) , one neutron ejected from each fission causes
10、 another fission to occur. The process of capturing the neutron and splitting happens very quickly, on the order of picoseconds ( 11012seconds). An incredible amount of energy is released, in the form of heat and gamma radiation, when a single atom splits. The two atoms that result from the fission
11、later release beta radiation and gamma radiation of their own as well. The energy released by a single fission comes from the fact that the fission products and the neutrons, together, weigh less than the original U-235 atom. The difference in weight is converted directly to energy at a rate governe
12、d by the equation E = mc2. In order for these properties of U-235 to work, a sample of uranium must be enriched so that it contains 2 percent to 3 percent or more of uranium-235. Three-percent enrichment is sufficient for use in a civilian nuclear reactor used for power generation. Weapons-grade ura
13、nium is composed of 90-percent or more U-235. Inside a Nuclear Power Plant To build a nuclear reactor, what you need is some mildly enriched uranium. Typically, the uranium is formed into pellets (芯块 ) with approximately the same diameter as a coin and a length of an inch or so. The pellets are arra
14、nged into long rods, and the rods are collected together into bundles. The bundles are then typically submerged in water inside a pressure vessel. The water is used to lower the heat. In order for the reactor to work, the bundle, submerged in water, must be slightly supercritical. That means that, l
15、eft to its own devices, the uranium would eventually overheat and melt. To prevent this, control rods (棒 ) made of a material that absorbs neutrons are inserted into the bundle. Raising and lowering the control rods allow operators to control the rate of the nuclear reaction. When an operator wants
16、the uranium core to produce more heat, the rods are raised out of the uranium bundle. To create less heat, the rods are lowered into the uranium bundle. The rods can also be lowered completely into the uranium bundle to shut the reactor down in the case of an accident or to change the fuel. The uran
17、ium bundle acts as an extremely high-energy source of heat. It heats the water and turns it to steam. The steam drives a steam turbine, which spins a generator to produce power. In some reactors, the steam from the reactor goes through a secondary, intermediate heat exchanger to convert another loop
18、 of water to steam, which drives the turbine. Outside a Nuclear Power Plant Once you get past the reactor itself, there is very little difference between a nuclear power plant and a coal-fired or oil-fired power plant except for the source of the heat used to create steam. The reactors pressure vess
19、el is typically housed inside a concrete liner that acts as a radiation shield. That liner is housed within a much larger steel containment vessel. This vessel contains the reactor core as well the hardware that allows workers at the plant to refuel and maintain the reactor. The steel containment ve
20、ssel is intended to prevent leakage of any radioactive gases or fluids from the plant. Finally, the containment vessel is protected by an outer concrete building that is strong enough to survive such things as crashing jet airliners. These secondary containment structures are necessary to prevent th
21、e escape of radiation/radioactive steam in the event of an accident like the one at Three Mile Island. The absence of secondary containment structures in Russian nuclear power plants allowed radioactive material to escape in an accident at Chernobyl. What Can Go Wrong Well-constructed nuclear power
22、plants have an important advantage when it comes to electrical power generation-they are extremely clean. Compared with a coal-fired power plant, nuclear power plants are a dream come true from an environmental standpoint. A coal-fired power plant actually releases more radioactivity into the atmosp
23、here than a properly functioning nuclear power plant. Coal-fired plants also release tons of carbon, sulfur and other elements into the atmosphere. Unfortunately, there are significant problems with nuclear power plants: Mining and purifying uranium has not, historically, been a very clean process.
24、Improperly functioning nuclear power plants can create big problems. The Chernobyl disaster is a good recent example. Spent fuel from nuclear power plants is toxic (有毒的 ) for centuries, and, as yet, there is no safe, permanent storage facility for it. Transporting nuclear fuel to and from plants pos
25、es some risk, although to date, the safety record in the United States has been good. These problems have largely derailed the creation of new nuclear power plants in the United States. Society seems to have decided that the risks outweigh the rewards. 2 There are over 00 hundred nuclear power plant
26、s in the world, most of the them are in Europe. （ A） Y （ B） N （ C） NG 3 Scientists believe that uranium was absorbed by the Earth when it was formed. （ A） Y （ B） N （ C） NG 4 The German government has decided to reduce its dependence on electricity generated by nuclear power. （ A） Y （ B） N （ C） NG 5
27、A nuclear fission is a process of a U-23 nucleus with a neutron trying to capture another neutron. （ A） Y （ B） N （ C） NG 6 Uranium has to be enriched if a nuclear reactor is built. （ A） Y （ B） N （ C） NG 7 Control rods in a nuclear reactor are used to control the amount of energy generated in a nucle
28、ar reactor. They can also be used to shut the reactor or to change the fuel. （ A） Y （ B） N （ C） NG 8 Mining and purifying uranium do not cause any environmental damage. （ A） Y （ B） N （ C） NG 9 A nuclear reactor is protected by _ , a concrete radiation shield, a steel containment vessel, and an outer
29、 concrete building. 10 The result of nuclear fission is to release energy in the form of _. 11 The present solution to dispose _ is yet to be found as it remains toxic for a fairly long time. Section A Directions: In this section, you will hear 8 short conversations and 2 long conversations. At the
30、end of each conversation, one or more questions will be asked about what was said. Both the conversation and the questions will be spoken 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.
31、（ A） Looking for a timetable. （ B） Buying some furniture. （ C） Reserving a table. （ D） Window shopping. （ A） How to deposit money. （ B） How to write a cheque. （ C） How to calculate the interest rate. （ D） How to open a current account. （ A） In the top right-hand corner. （ B） In the box printed on th
32、e cheque. （ C） On the right-hand bottom line. （ D） On the back of the cheque. （ A） In words. （ B） In numbers. （ C） Both in words and in numbers. （ D） In none of the above ways. （ A） An interview between two companies. （ B） An interview between an employer and an applicant. （ C） An interview between
33、an employer and an employee. （ D） An interview by a talk show hostess. （ A） He has worked in a trading company. （ B） He majored in English Literature in university. （ C） He has worked for an American company for 4 years. （ D） He has studied in the U. S. A. for half a year. （ A） He wants more challen
34、ging work. （ B） He wants to earn more money. （ C） He wants to enjoy more freedom. （ D） He is not satisfied with the company. （ A） The man has to wait for some further notice. （ B） The man has to go back to his trading company. （ C） The man has failed to get the job. （ D） The man has succeeded in app
35、lying for the job. Section B Directions: In this section, you will hear 3 short passages. 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,
36、B, C and D. （ A） Men suffer more than women when pretending to be happy. （ B） Smiling for the sake of smiling makes one feel gloomier. （ C） Faking smile is a necessary factor in customer-service work. （ D） Putting a smiling face on ones sorrow is good for his health. （ A） Because it masks the true f
37、eelings of the workers. （ B） Because it leads to more complaints from the workers. （ C） Because it prevents the workers from recalling pleasant memories. （ D） Because it makes the workers feel emotionally exhausted and withdraw. （ A） They are more likely to be fired. （ B） They benefit more from deep
38、 acting. （ C） They benefit more from surface acting. （ D） They are more likely to feel happy in work. （ A） They are not well educated. （ B） They failed to work hard at school. （ C） The society is too complicated. （ D） What they learned in the school is adequate for their new life. （ A） To find a wor
39、ker and follow him closely. （ B） To find a person you admire and make friends with him. （ C） To find a person you respect and watch carefully how he acts. （ D） To make friends with a model you admire. （ A） Learn From a Model （ B） Learn, Learn and Learn Again （ C） Leant Forever （ D） One Is Never Too
40、Old to Learn （ A） During mating season. （ B） Except during the mating season. （ C） All the year round. （ D） Only in spring. 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
41、the passage 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 h
42、eard or write down the 26 If you were to stop people in the street and ask them to name a ship that had been sunk, it is likely that nearly all of them would say the Titanic. For the【 B1】 _of the Titanic was, if not the most【 B2】 _, certainly the most famous sea disaster in the history of ocean【 B3】
43、 _. The Titanic was built as a luxury liner, intended to be the fastest in the world, and a great deal of publicity had【 B4】 _it. The last point probably explains why so many important people from all【 B5】 _of life were on the boat when it went down. The Titanic was on its maiden【 B6】 _to America in
44、 1921 when it【 B7】_an iceberg and sunk. Of its 2,200 passengers, more than two-third were drowned. Because the Titanic was thought to be【 B8】 _unsinkable, no one was prepared for the tragedy.【 B9】 _. There was a severe shortage of lifeboats and those that were launched were still half-empty. The one
45、 point of calm was to be found in the ballroom where the band carried on playing right to the very end.【 B10】 _. In addition, one ship was only ten miles away, but did not receive the distress call. One good thing did, however, result from the disaster.【 B11】 _. 27 【 B1】 28 【 B2】 29 【 B3】 30 【 B4】 3
46、1 【 B5】 32 【 B6】 33 【 B7】 34 【 B8】 35 【 B9】 36 【 B10】 37 【 B11】 Section A Directions: In this section, there is a passage with ten blanks. You are required to select one word for each blank from a list of choices given in a word bank following the passage. Read the passage through carefully before m
47、aking your choices. Each choice in the bank is identified by a letter. Please mark the corresponding letter for each item with a single line through the center. You may not use any of the words in the bank more than once. 37 Hungry prehistoric bunters, not climate change, drove elephants to extincti
48、on during the Pleistocene era(更新世 ), new research suggests. At least 12 kinds of elephants【 S1】 _to wander about the African, Eurasian, and American continents. Today, only two【 S2】 _of elephants are left in South Asia and Africa. One theory for this dramatic death holds that rapid climate shifts at
49、 the end of the most recent major ice age, some 10,000 years ago,【 S3】 _vegetation and broke up habitats(栖息地 ), causing the death of those unable to adapt to the new conditions. Another【 S4】 _blames prehistoric humans, whose improved weapons and hunting techniques allowed them to wipe out whole herds of elephants. To hel
