2000年9月全国计算机等级考试四级笔试试题
2000年大学英语四级真题
2000年全国英语专业四级考试试题英美者 英语专业网站来源:英美者英语专业网站作者:全国英语专业四级八级考试委员会[编辑]导言:2000年全国英语专业四级考试试题Part ⅠWRITING ［45 MIN.］SECTION A COMPOSITIONWrite on ANSWER SHEET ONE a composition of about 150 words on the following topic: College life should be varied and colourful. And extracurricular activities are an important aspect of it. However, at present, there is much room for improveme nt in this regard. Write an article to the university radio entitled:The Importance of Extracurricular ActivitiesIn the first part of your article you should clearly present yourview, and in t he second part you should support your opinion with appropriate details. In the last part you should bring what you have written to a natural conclusion or summ ary.Marks will be awarded for content, organization, grammar and appropriacy. Failur e to follow the above instructions may result in a loss of marks.SECTION B NOTE-WRITING［10 MIN.］Write on ANSWER SHEET ONE a note of about 50-60 words based on the following situation:You’ve read on the notice board that the university library is looking for a par t-time library assistant who can work at weekends. You think that your classmate , George, is a suitable person for this vacancy. Write him a note, telling him w hat you know about the vacancy and trying to persuade him to go for an interview Marks will be awarded for content organization, grammar and appropriacy.Part ⅡDICTATION ［15 MIN.］Listen to the following passage. Altogether the passage will be read to you four times. During the first reading, which will be read at normal speed, listen and try to understand the meaning. For thesecond and third readings, the passage w ill be read sentence by sentence, or phrase by phrase, with intervals of 15 seco nds. The last reading will be read at normal speed again and during this time yo u should check your work. You will then be given 2 minutes to check through your work once more. Please write the whole passage on ANSWER SHEET TWOPart ⅢLISTENING COMPREHENSION ［20 MIN.］ In Sections A, B, and C you will hear everything ONCE ONLY. Listen carefully an d then answer the questions that follow. Mark the best answer to each question o n your answer sheet.Section A STATEMENTIn this section you will hear nine statements. At the end of the statement you w ill be given 10 seconds to answer each of the following nine questions. 1. What is said about Harry’s brother?A. He is happy with his job.B. He is a very ambitious man.C. He is too ambitious to be an engine driver.D. He doesn’t like to be an engine driver.2. What do you learn about Ms. Ellis?A. She has been waiting.B. She is examining her patient.C. She is seeing her doctor.D. She wouldn’t mind waiting.3. Joan is probably a___.A. nurseB. doctorC. lawyerD. saleswoman4. The speaker sees Mary wear ___ different silk scarves in a wee k.A. 2B.5C.7D. 65. Where will the passengers change trains to go to Gilford?A. East Croydon.B.Victoria.C. Southeast.D.Red Hill.6. What is the speaker probably doing?A. Interviewing a clerk.B. Writing a job ad.C. Dismissing a clerk.D. Making inquires7. What does the speaker mean?A. Emily is neither honest nor trustworthy.B. Emily used to be honest only.C. Emily used to be trustworthy only.D. Emily is more than honest and trustworthy.8. When does the next train leave?A. 6:56.B. 7:00.C.7:28.D.8:38.9. What was wrong with Malcolm?A. He had trouble working hard.B. He didn’t know where to go.C. He never went anywhere.D. He worked hard but never succeeded.SECTION B CONVERSATIONIn this section, you will hear eight short conversations between two speakers. A t the end of each conversation you will be given 10 seconds to answer each of th e following eight questions.10. What’s the probable relationship between the two speakers?A. Teacher and student.B. Doctor and patient.C. Lawyer and client.D. Boss and secretary.11. What is the weather usually like in November?A. Hotter than the present weather.B. More humid than the present weather.C. Drier than the present weather.D. Cooler than the present weather.12. What conclusion can we draw from this conversation?A. Public buses are fast and cheap.B. Parking is becoming a big problem.C. Subway trains are even safer than taxis.D. Taxis are more convenient than buses.13. What are the two speakers talking about?A. Fixing the woman’s computer.B. Ordering some new parts by Friday.C. Getting the new parts ready by Friday.D. Sending the woman’s computer for repair.14. What can we learn from the conversation?A. Neither of them has a favourable opinion of the service.B. The woman is having a terrible time serving in the restaurant.C. Both agree it’s time for the restaurant to fire some staff.D. The man thinks the restaurant is all right, but the woman doesn’t.15. Who will pay for the call?A. The man.B. The operator.C. The man’s sister.D. The man and his sister.16. What does the man think of the woman’s choice of clothing?A. He thinks her choice is good.B. He thinks her choice is terrible.C. He doesn’t like the colour.D. He doesn’t like the style.17. What happened to Mr. Runt’s project?A. It was fairly successful.B. It was hard and futile.C. It failed for lack of fund.D. It stopped for lack of land.SECTION C NEWS BROADCASTQuestion 18 is based on the following news. At the end of the news item, you wil l be given 1O seconds to answer the question.Now listen to the news.18. According to the news, NATO and Russia___.A. have finalized a charter on their new relationshipB. still have differences in military and political issuesC. will hold a fifth round of talks in LuxembourgD. made no progress in this round of talksQuestions 19 and 20 are based on the following news. At the end of the news item , you will be given 20 seconds to answer the two questions.Now listen to the news.19. ___ people were killed during the air crash.A. 61B. 51C. 41D.1020. According to the news, the plane crashed___.A. shortly before it landedB. minutes after it took offC. after it cleared the mountainsD. at the foot of the mountainsQuestions 21 and 22 are based on the following news. At the end of the news item , you will be given 20 seconds to answer the two questions.Now listen to the news.21. Which of the following is NOT listed as a terrorist group by the US ?A. The pro-Iranian Hezbollah.B. The Palestinian group Hamas.C. The Irish Republican Army.D. The Basque separatist group ETA.22. The affected groups will be prevented from___.A. entering the United States legallyB. freezing US financial assets abroadC. receiving support from other countriesD. giving weapons to other terrorist groupsQuestion 23 is based on the following news. At the end of the news item, you wil l be given 1O seconds to answer the question.Now listen to the news.23. Israeli Prime Minister Benjamin Netanyahu___.A. has been prosecuted by the Justice MinistryB. may be prosecuted by the Justice MinistryC. has been prosecuted by the policeD. will be prosecuted on MondayQuestions 24 and 25 are based on the following news. At the end of the news item , you will be given 20 seconds to answer the two questions.Now listen to the news.24. The winners of the reported elections are___.A. the left-wing ConservativesB. the left-wing SocialistsC. the centre-right ConservativesD. the centre-right Socialists25. If the left secures the parliamentary majority,___.A. Chirac will share his presidential power with JospinB. Jospin will share his prime ministerial power with ChiracC. Jospin will become prime minister, and Chirac will remainD. Jospin will become prime minister, and Chirac will resign完型填空Part ⅣCLOZE ［15 MIN.］Decide which of the choices given below would best complete the passage if inserted in the corresponding blanks. Mark the best choice for each blank on your answer sheet.The difference between a liquid and a gas is obvious ( 26 ) the conditions of temperature and pressure commonly found at the sur face of the Earth. A liquid can be kept in an open container and ( 27 ) it to the level of a free surface. A gas forms no free surface but ( 28 ) to diffuse throughout the space available; it must ( 29 ) be kept in a closed container, as ( 30 ) aplanet’s atmosphere. The distinction was a prominent feature of early theories ( 31 )the phases of matter. In the nineteenth century, for example, one theory maintained that a liquid could be “dissolved”in a vapor without losing its identity, and another theory held that the two phases are ( 32 ) different kinds o f molecules(分子). The theories now prevailing ( 33 ) a quit e different approach by emphasizing what liquids and gases have in common. They are both forms of matter that have no permanent structure, and they both flow ea sily. They are fluids.The ( 34 ) similarly of liquids and gases becomes clear ly apparent when the temperature and pressure are raised somewhat. ( 35 ) a closed container partially filled with a liquid is heated. The li quid expands or ( 36 ) , becomes less dense; some of it evapor ates. ( 37 ) , the vapor above the liquid surface becomes dense r as the evaporated molecules are added to it. The combination of temperature an d pressure ( 38 ) the densities become equal is ( 3 9 ) the critical point. Above the critical point the liquid and the gas can no longer be ( 40 ) ; there is a single, undifferentiated fluid phase of uniform density.26. A. in B. on C. under D. beyond27. A. fills B. be filled C. filling D. to fill28. A. intends B. tends C. inclines D. contends29. A. however B. nevertheless C. so D. therefore30． A. in the event of B. in the case of C. with a view to D. with reference to31. A. having described B. described C. describing D. to have described32. A. made up of B. consisted of C. constituted of D. made from33. A. apply B. adapt C. take D. conduct34. A. elementary B. crucial C. rudimentaryD. fundamental35. A. Suppose B. To suppose C. Being supposed D. Supposed36. A. in a word B. in the meantime C. in other words D. in that case37. A. Similarly B. In contrast C. Furthermore D. Instead38. A. on that B. on which C. at that D. at which39. A. known B. defined C. called D. referred to40. A. classified B. recognized C. categorized D. distinguished转自[英美者]-英语专业网站：/cn/Html/TEM/Test4/7393488198093.html2000年全国英语专业四级考试试题Part ⅤGRAMMAR AND VOCABULARY ［15 MIN.］There are twenty-five sentences in this section. Beneath each sentence there are four words or phrases marked A, B, C and D. Choose one word or phrase that best completes the sentence. Mark your answers on your answer sheet.41. Acute hearing helps most animals sense the approach of thunderstorm s long before people___.A. doB. hearC. do themD. hearing it42. This is an illness that can result in total blindness ___ left u ntreated.A. afterB. ifC. sinceD.unless43. The central provinces have floods in some years, and ___.A. drought in othersB. droughts are othersC. while other droughtsD. others in drought44. Do help yourself to some fruit,___ you?A. can’tB. don’tC. wouldn’tD. won’t45. There___ nothing more for discussion, the meeting came to an e nd half an hour earlier.A. to beB. to have beenC. beingD.be46. My mother can’t get ___ because she has rheumatism (风湿病).A. aboutB.onC. throughD. in47. I was very much put ___ by Mark’s rude behavior; it really annoy ed me.A.overB.offC.upD.by48. You ___ Jim anything about it. It was none of his business.A. needn’t have toldB. needn’t tellC. mustn’t have toldD. mustn’t tell49. All of us would have enjoyed the party much more if there___ q uite such a crowd of people there.A. weren’tB. hasn’t beenC. hadn’t beenD.w ouldn’t be50. Firms that use computers have found that the number of staff ___ quality control can be substantially reduced.A.whoseB.asC.whatD.that51. ___ at in this way, the present economic situation doesn’t seem so gloomy.A. LookingB. LookedC. Having lookedD. To look52. Many people are ___ to insect bites, and some even have to go to hospital.A. insensitiveB. allergicC. sensibleD. infected53. When you’re driving on a motorway, you must obey the signs telling you to get into the right ___.A.wayB.trackC.roadne54. The motorist had to ___to avoid knocking the old woman down in the middle of the road.A. swerveB. twistC. departD. swing55. In winter drivers have trouble stopping their cars from ___ on icy roads.A. skatingB. skiddingC. slidingD. slipping56. This project would ___ a huge increase in defense spending.A. resultB. assureC. entailD. accomplish57. The chances of a repetition of these unfortunate events are ___ indeed.A. distantB. slimC. unlikelyD. narrow58. We should make a clear ___ between ’competent’and ’proficient’for the purposes of our discussion.A. separationB. divisionC. distinctionD. diffe rence59. In the present economic ___ we can make even greater progress than previously.A. airB. moodC. areaD. climate60. Rite of Passage is a good novel by any standards;___, it shoul d rank high on any list of science fiction.A. consistentlyB. consequentlyC. invariablyD. fortunately61. The diversity of tropical plants in the region represents a seeming ly___ source of raw materials, of which only a few have been utilized.A. exploitedB. controversialC. inexhaustibleD.remarkable62. While he was in Beijing, he spent all his time ___ some import ant museums and buildings.A. visitingB. travelingC. watchingD. touring63. You must let me have the annual report without ___ by ten o’cl ock tomorrow morning.A. failureB. hesitationC. troubleD. fail64. As the director can’t come to the reception, I’m representing the c ompanyA. on his accountB. on his behalfC. for his partD. in his interest65. Dreams are___ in themselves, but when combined with other data, they can tell us much about the dreamer.A. uninformativeB. startlingC.harmless D. uncontrollable阅读理解APart ⅥREADING COMPREHENSION ［30 MIN.］ SECTION A READING COMPREHENSION［25 MIN.］In this section there are four passages followed by questions or unfinished stat ements, each with four suggested answers marked A, B, C and D. Choose the one th at you think is the best answer. Mark your answers on your answer sheet.TEXT AClearly if we are to participate in the society in which we live we must communi cate with other people. A great deal of communicating is performed on a person-t o-person basis by the simple means of speech. If we travel in buses, buy things in shops, or eat in restaurants, we are likely to have conversations where we gi ve information or opinions, receive news or comment, and very likely have our vi ews challenged by other members of society.Face-to-face contact is by no means the only form of communication and during th e last two hundred years the art of mass communication has become one of the dom inating factors of contemporary society. Two things, above others, have caused t he enormous growth of the communication industry. Firstly, inventiveness has led to advances in printing, telecommunications, photography, radio and television. secondly, speed has revolutionised the transmission and reception of communicat ions so that local news often takes a back seat to national news, which itself i s often almost eclipsed by international news.No longer is the possession of information confined to a privileged minority. In the last century the wealthy man with his own library was indeed fortunate, but today there are public libraries. Forty years ago people used to flock to the c inema, but now far more people sit at home and turn on the TV to watch a program me that is being channelled into millions of homes. Communication is no longer merely concerned with the transmission of information . The modem communication industry influences the way people live in society and broadens their horizons by allowing access to information, education and entert ainment. The printing,broadcasting and advertising industries are all involved with informing, educating and entertaining.Although a great deal of the material communicated by the mass media is very val uable to the individual and to the society of which he is a part, the vast modem network of communications is open to abuse. However, the mass media are with us for better, for worse, and there is no turning back.66. In the first paragraph the writer emphasizes the___ of face-t o-face contact in social settings.A. natureB. limitationC. usefulnessD. creativity67. It is implied in the passage that___.A. local news used to be the only source of information.B. local news still takes a significant place.C. national news is becoming more popular.D. international news is the fastest transmitted news.68. Which of the following statements is INCORRECT?A. To possess information used to be a privilege.B. Public libraries have replaced private libraries.C. Communication means more than transmission.D. Information influences ways of life and thinking.69. From the last paragraph we can infer that the writer is___.A. indifferent to the harmful influence of the mass mediaB. happy about the drastic changes in the mass mediaC. pessimistic about the future of the mass mediaD. concerned about the wrong use of the mass mediaTEXT BThe men and women of Anglo-Saxon England normally bore one name only. Distinguis hing epithets were rarely added. These might be patronymic, descriptive or occup ational. They were, however, hardly surnames. Heritable names gradually became g eneral in the three centuries following the Norman Conquest in 1066. It was not until the 13th and 14th centuries that surnames became fixed, although for many years after that, the degree of stability in family names varied considerably in different parts of the country.British surnames fall mainly into four broad categories: patronymic,occupationa l, descriptive and local. A few names, it is true, will remain puzzling: foreign names, perhaps, crudely translated, adapted or abbreviated; or artificial names . In fact, over fifty per cent of genuine British surnames derive from place names of different kinds, and so they belong to the last of our four main categories. Even such a name as Simpson may belong to this last group, and not to the first , had the family once had its home in the ancient village of that name. Otherwis e, Simpson means “the son of Simon”, as might be expected.Hundreds of occupational surnames are at once familiar to us, or at least r ecognisable after a little thought: Archer, Carter, Fisher, Mason, Thatcher, Tay lor, to name but a few. Hundreds of others are more obscure in their meanings an d testify to the amazing specialisation in medieval arts, crafts and functions. Such are “Day”, (Old English for breadmaker) and “Walker”(a fuller whose job it was to clean and thicken newly made cloth).All these vocational names carry with them a certain gravity and dignity, w hich descriptive names often lack. Some, it is true, like “Long”, “Short” or “Li ttle”, are simple. They may be taken quite literally. Others require more thinki ng: their meanings areslightly different from the modem ones. “Black”and “White ”implied dark and fair respectively. “Sharp”meant genuinely discerning, alert, acute rather than quick-witted or clever. Place-names have a lasting interest since there is hardly a town or village in a ll England that has not at some time given its name to a family. They may be pic turesque, even poetical; or they may be pedestrian, even trivial. Among the comm oner names which survive with relatively little change from old-English times ar e “Milton”(middle enclosure) and “Hilton”(enclosure on a hill).70. Surnames are said to be ___ in Anglo-Saxon England.A. commonB. vocationalC. unusualD. descriptiv e71. We learn from the first paragraph ___ for many years after the 13th and 14th centuries.A. family names became descriptive and occupationalB. people in some areas still had no surnamesC. some people kept changing their surnamesD. all family names became fixed in England72. “Patronymic”in the second paragraph is closest in meaning to“forme d from ___.A. the name of one’s father”B. the family occupation”C. one’s family home”D. one’s family history”73. Which of the following sentences is an opinion rather than a fact?A. hundreds of occupational names are at once familiar to us.B. “Black”and “White”implied “dark”and “fair”respectively.C. V ocational names carry with them a certain gravity and dignity.D. Every place in England has given its name to a family. TEXT CSince the early 1930s, Swiss banks had prided themselves on their system of banking secrecy and numbered accounts. Over the years, they had successfully w ithstood every challenge to this system by their own government who, in turn, ha d been frequently urged by foreign governments to reveal information about the f inancial affairs to certain account holders. The result of this policy of secre cy was that a kind of mystique had grown up around Swissbanking. There was a w idely-held belief that Switzerland was irresistible to wealthy foreigners, mainl y because of its numbered accounts and bankers’ reluctance to ask awkward questi ons of depositors. Contributing to the mystique was the view, carefully propagat ed by the banks themselves, that if this secrecy was ever given up, foreigners w ould fall over themselves in the rush to withdraw money, and the Swiss banking s ystem would virtually collapse overnight.To many, therefore, it came like a bolt out of the blue, when, in 1977, the Swiss banks announced they had signed a pact with the Swiss National Bank (the Central Bank). The aim of the agreement was to prevent to improper use of the c ountry’s ban k secrecy laws, and its effect was to curb severely the system of se crecy.The rules which the banks had agreed to observe made the opening of numbere d accounts subject to much closer scrutiny than before. The banks would be requ ired, if necessary, to identify the origin of foreign funds going into numbered and other accounts. The idea was to stop such accounts being used for dubious p urposes. Also they agreed not to accept funds resulting from tax evasion or from crime.The pact represented essentially a tightening up of banking rules. Although the banks agreed to end relations with clients whose identities were unclear or who were performing improper acts, they were still not obliged to inform on a client to anyone, including the Swiss government. To some extent, therefore, the princ iple of secrecy had been maintained.74. Swiss banks took pride in___.A. the number of their accountsB. withholding client informationC. being mysterious to the outsidersD. attracting wealthy foreign clients75. According to the passage, the widely-held belief that Switzerland w as irresistible to wealthy foreigners was ___ by banks themselves.A. deniedB. criticizedC. reviewedD. defended76. In the last paragraph, the writer thinks that___.A. complete changes had been introduced into Swiss banksB. Swiss banks could no longer keep client informationC. changes in the bank policies had been somewhat superficialD. more changes need to be considered and madeTEXT DCoketown was a town of red brick, or of brick that would have been red if the sm oke and the ashes had allowed it; but as matters stood it was a town of unnatura l red and black like the painted face of a savage. It was a town of machinery an d tall chimneys, out of which smoke trailed themselves for ever and ever. It had a black canal in it, and a river that ran purple with ill-smelling dye, and vas t piles of buildings full of windows where there was a rattling and a trembling all day long, and where the piston of the steam-engine worked monotonously up an d down like the head of an elephant in a state of madness. The town contained se veral large streets all very like one another, and many small streets still more like one another, inhabited by people equally like one another.A sunny midsummer day. There was such a thing sometimes, even in Coketown. Seen from a distance in such weather, Coketownlay covered in a haze of its own. You only knew the town was there, because you knew there could have been no such blo tch upon the view without a town.The streets were hot and dusty on the summer day, and the sun was so bright that it even shone through the haze over Coketown, and could not be looked at steadi ly. Workers emerged from low underground doorways into factory yards, and sat on posts and steps, wiping their faces and contemplating coals. The whole town see med to be frying in oil. There was a stifling smell of hot oil everywhere. The a tmosphere of those places was like the breath of hell, and their inhabitants was ting with heat, toiled languidly in the desert. But no temperature made the mad elephants more mad or more sane. Their wearisome heads went up and down at the s ame rate, in hot weather and in cold, wet weather and dry fair weather and foul. The measured motion of their shadows on the walls, was the substitute Coketown had to show for the shadows of rustling woods; while for the summer hum of insec ts, it could offer all the year round, from the dawn of Monday to the night of S aturday, the whirr of shafts and wheels.77. Which of the following adjectives is NOT appropriate todescribe Co ketown?A. dullB. dirtyC. noisyD. savage78. From the passage we know that Coketown was mainly a(n) ___town .A. industrialB. agriculturalC. residentialD. commercial79. Only ___ were not affected by weather.转自[英美者]-英语专业网站：/cn/Html/TEM/Test4/7393488198093_2.ht ml2000年全国英语专业四级考试试题A. the workmenB. the inhabitantsC. the steam-enginesD. the rustling woods80. Which is the author’s opinion of Coketown?A. Coketown should be replaced by woods.B. The town was seriously polluted.C. The town had too much oil in it.D. The town’s atmosphere was traditional.BSECTION B SKIMMING AND SCANNINGIn this section there are seven passages with a total often multiple-choice ques tions. Skim or scan them as required and then mark your answers on your answer s heet.TEXT EFirst read the following question.81. The writer is concerned about___.A. budget housekeepingB. the retail tradeC. computer skillsD. mental arithmeticNow read Text E quickly and mark your answer on your answer sheet.A lot of attention is being given to children who leave school unable to read or write. I think there should be equal concern for those who are unable to cope w ith simple mental arithmetic -particularly girls. It is often stated that today’s children are growing up in a computer world and they don’t need the same skills that their grandparents did. But is it any wonde r that many young girls trying to cope with budget housekeeping fail for the sim ple reason they cannot keep accurate checks on their purchases? Shopping in markets is no source of cheap purchasing unless one is able to keep pace with the apparent mental agility of the vendor. Must we face the thought that at some time in the distant future everyone will n eed to carry in their handbag or pocket one of the miniature calculators?TEXT FFirst read the following question.82. This is a letter of___.A. referenceB. applicationC. inquiryD. complaint。
计算机四级考试试题含答案3篇
计算机四级考试试题含答案第一篇：听力部分一、听力理解Passage 11. A) He wasted a lot of time on the Internet.2. B) He had to work harder to make up for the lost time.3. C) He found it easier to manage his time after the incident.Passage 24. A) Children’s entertainment.5. B) A new type of TV program.6. D) It helps children learn without realizing it.Passage 37. A) His experience as a gardener.8. C) The latest methods of gardening.9. B) Making full use of available space for gardening.Passage 410. D) They have difficulty expressing themselves in a foreign language.11. B) They may show their true personality more in a foreign language.12. C) They have a hard time understanding the humor in a foreign language.二、听力填空Section A: Directions: In this section, you will hear 10 short conversations. At the end of each conversation, a question will be asked about what was said. Both the conversation and the question will be spoken only once. After each question there will be a pause. During the pause, you must read the fourchoices marked A), B), C) and D), and decide which is the best answer. Then mark the corresponding letter on the Answer Sheet with a single line through the center.1. type of shirt she wants2. He has to leave very early in the morning.3. The woman’s plan to study in the library.4. The woman has been admitted to the university.5. Jenny has to buy more books than she expected.6. Buy a bigger bag.7. The fact that the train is late.8. She will return the book to the library.9. He is going to buy a new bike soon.10. He is going to go to the stadium later this afternoon.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 aquestion, you must choose the best answer from thefour choices marked A), B), C) and D). Then mark the corresponding letter on the Answer Sheet with a single line through the center.11. Why do people who exercise have better vision?12. What should you do if you want to prevent the loss of vision?13. What kind of food is rich in vitamin A?14. Why is working in dim light bad for your eyes?15. How does lack of sleep affect your vision?三、听力短文Passage One16. C) Take more public transportation.17. A) Reduce pollution.18. B) Provide more job opportunities.Passage Two19. B) Help improve their life skills.20. C) Teach them how to deal with emergencies.21. A) To eliminate surprises that could be dangerous.Passage Three22. C) They produce extra food for emergencies.23. B) They are a symbol of health and prosperity.24. D) They are a source of innovation.Passage Four25. B) Furniture made of recycled materials.26. C) Chemicals that can be hazardous to yourhealth.27. A) How to avoid the risks of indoor pollution.第二篇：阅读部分一、阅读选词填空1. J) set2. A) maximize3. D) demonstrate4. N) exposure5. I) alternative6. K) establish7. H) constitute8. G) grade9. B) survival10. F) clarify11. M) acquisition12. E) restrict13. L) skeptical二、完形填空1. C) interrupted2. D) bored3. A) expensive4. A) not really5. B) surprising6. D) refuse7. C) occasionally8. A) similarly9. D) unless10. C) history11. A) adopt12. B) creative13. C) alternatively14. D) lack15. C) explores三、阅读理解Passage one:1. A) By increasing taxes on sugary drinks.2. D) It is becoming more difficult to find too much sugar in food.3. B) Some of the polls conducted by the government had poor methods.4. C) The government encourages food companies to reduce sugar in their products.5. D) Britain’s sugar reduction program is currently far from achieving its goal.Passage two:6. D) How humans learn from music.7. D) It provokes our feelings and curiosity.8. C) They share a lot of similarities with child conversations.9. B) To raise our interest in the topic.10. C) By dividing it into smaller, easier-to-understand parts.Passage three:11. A) They were unaware of security threats.12. B) Problems with the security clearance process.13. C) They pose potential security risks.14. D) Attackers could take control of engines and other vital systems.15. B) A lack of awareness of cybersecurity risks among users.第三篇：写作部分一、作文Dear Mr. Smith,I am writing to express my strong objection tothe recent decision to cancel school sports programs in our district. While I understand that budget cuts may be challenging, I believe that cutting sports programs is not the best solution. As a student-athlete, I have experienced firsthand the manybenefits that sports programs bring to our schools.Firstly, sports programs encourage students to be physically active and lead healthy lifestyles. With childhood obesity rates on the rise, it is important to promote healthy habits in our schools. Furthermore, participation in sports can improve students’ mental and emotional well-being, as well as their academic performance.Secondly, sports programs provide students with valuable life skills. Learning to work together as a team and to persevere through challenges are importantskills that will serve students well in their future careers and personal lives. Sports also teach students important values such as sportsmanship, fair play and respect for others.Finally, sports programs are a source of pridefor our schools and communities. They provide opportunities for students to represent their schools on a local, regional or even national level and can help to build community spirit and support.In conclusion, I strongly urge you to reconsider the decision to cancel school sports programs. The benefits of these programs are far too important to ignore. Thank you for taking the time to consider my concerns.Yours sincerely,[Your Name]二、翻译1. 我的爷爷是个非常有趣的人。
2000专四真题参考答案
参考答案：PART ⅠWRITINGSECTION A［参考范文］The Importance of Extracurricular ActivitiesDear Editor,People have different ideas about how students should spend their school days. Some believe that students should spend the whole day on academic studies. Others believe that extracurricular activities should be a required part of every school day. I think both ways have their advantages. But I prefer the latter.As a student, our main task is to concentrate on our academic study. We have to attend classes, reading books and doing assignments. Only by working hard can we learn our courses well. But I don’t think we should spend every hour and minute on academic study. A proverb says, “All work and no play makes Jack a dull boy.” Without good health and strong body, how can we improve our study efficiency and make great achievements in our academic study? Besides, spending the whole day on academic study may make us exhausted and weak. We should find other meaningful things to do besides studying. For example, doing extracurricular activities can make students’ life more colorful and beneficial. There are various forms of exercise. My favorite one is football. I play football with my classmates for one hour every afternoon. After a day’s hard work, how nice it is to stretch my arms and legs! By playing football I’ve got both joy and strength. I always looken ergetic.Actually doing extracurricular activities doesn’t disturb our study if we make full use of our time. Instead it does help us study more efficiently. We can be good at learning as well as extracurricular activities. So I suggest that students do extracurricular activities along with their academic studies.SECTION B［参考范文］Dear George,I have read on the notice board that the university is looking for a part-time library assistance who can work at weekends. I think you are the suitable person for this vacancy, for you are free at weekends and it pays well, yet the job is not difficult. It is also a good chance to improve yourself. So you shouldgo for an interview.Yours完型填空短文大意：这篇文章介绍了气体与液体的特性及相关理论。
计算机四级证书试题及答案
计算机四级证书试题及答案（正文）第一部分：听力理解Section A（20 points）1. A) The woman doesn't have a flashlight.B) The man forgot to take his flashlight.C) There is no flashlight in the man's bag.D) The man can lend his flashlight to the woman.2. A) He agrees with the woman's statement.B) He disagrees with the woman's statement.C) He suggests finding a new place to live.D) He doesn't mind the noise from the street.3. A) The man was invited to the party.B) The man's friend had a birthday recently.C) The man has already bought a present.D) The man is planning to celebrate his birthday.4. A) They should not have waited for the bus.B) The bus will arrive later than scheduled.C) They will take the next bus together.D) The bus they wanted to take is very crowded.5. A) He often helps the woman with her work.B) He is too busy to attend the meeting.C) He doesn't feel like going to the meeting.D) He will just listen instead of taking part.Section B（10 points）6. So far, the computer program is functioning ______.7. The company has decided to implement a new ______ system.8. Consumer demand for their products has ______ over the past year.9. This software offers a range of features to ______ all your needs.10. The manager called a meeting to ______ the current situation.Section C（10 points）11. What is the lecture mainly about?12. What will students be able to do with the lab?13. What does the professor say about the lab assistant?14. What is the main problem with the lab schedule?15. What does the professor suggest students do if they want to use the lab?Section D（10 points）16. The word "technology" comes from the Greek word _____.17. Early computers were mainly used for ______ purposes.18. The first computer program was written by ______.19. ______ computers are typically large and expensive.20. What is the passage mainly discussing?（附加答案）1-5 DBCAD 6-10 well; management; increased; meet; assess 11-15 CACAC 16-20 technologia; military; Ada Lovelace; Analog; The history and development of computers（正文结束）。
计算机操作员四级考试题(附参考答案)
计算机操作员四级考试题（附参考答案）一、单选题（共65题，每题1分，共65分）1.PC机数据总线信号的状态是（）。
A、单向双态B、单向三态C、双向双态D、双向三态正确答案：D2.计算机病毒破坏的主要对象是（）。
A、CPUB、磁盘驱动器C、程序和数据D、磁盘片正确答案：C3.如要关闭工作簿，但不想退出Excel，可以单击（）。
A、“窗口”下拉菜单中的“隐藏”命令B、“文件”下拉菜单中的“关闭”命令C、“文件”下拉菜单中的“退出”命令D、关闭Excel窗口的按钮×正确答案：B4.Powerpoint2010制作的演示文稿文件扩展名是（）。
A、.pptxB、.xlsC、.docD、.fpt正确答案：A5.下列设备中，密封性最好的是（）。
A、电源B、光驱C、机箱D、硬盘正确答案：D6.在立式机长中，个人计算机的电源一般安装在（）。
A、中部B、顶部C、底部D、任意位置正确答案：B7.Linux系统中网络连接测试命令是（）。
A、pingB、nettestC、iprouteD、route正确答案：A8.在因特网中，地址解析协议ARP是用来解析（）。
A、IP地址与MAC地址的对应关系B、MAC地址与端口号的对应关系C、IP地址与端口号的对应关系D、端口号与主机名的对应关系正确答案：A9.有关WinRAR软件说法错误的是（）。
A、WinRAR默认的压缩格式是RAR，它的压缩率比ZIP格式高出10%~30%B、WinRAR可以为压缩文件制作自解压文件C、WinRAR不支持ZIP类型的压缩文件D、WinRAR可以制作带密码的压缩文件正确答案：C10.Powerpoint2010提供的幻灯片模板，主要是解决幻灯片的（）。
A、文字格式B、文字颜色C、背景图案D、以上全是正确答案：D11.如果在A1、B1和C1三个单元格分别输入数据1、2和3，再选择单元格D4，然后单击常用工具栏中的按钮“∑”，则在单元格D1显示（）。
计算机四级考试试题含答案
计算机四级考试试题含答案一、听力部分1.听力理解1.1 短对话1. A. 家里太吵了，影响学习。
B. 我每天都去图书馆学习，想要尝试一下吗？A. 好的，那我们什么时候去？B. 最好是周末，这样时间比较宽裕。
Q: 周末他们想去哪里？A: 图书馆1.2 长对话2. A. 我在网上看到一个新款电子产品，非常不错，价格也很实惠。
B. 那我们去商场看看，实物跟网上一定有些不同。
A. 我查了一下，最便宜的商家在那个商场的三楼。
B. 所以你已经知道去哪个商场了？Q: 他们为什么要去商场？A: 去看电子产品1.3 长对话3. A. 你怎么那么熟练地使用电脑？B. 我是参加过一些计算机课程的，技术还是有一定水平的。
A. 你学习的哪些课程对你帮助最大？B. 最有帮助的是网络编程课程，它让我对计算机有了更深入的理解。
Q: 对B最有帮助的是哪个课程？A: 网络编程课程2.长篇听力2.1 短文听力4. 银行「金融家」们正在研究一种全球性的金融卡，它将可替代现有的信用卡和ATM卡。
金融卡将通过互联网版的电子商务进行支付和交易。
这种卡还将提供一种安全的电子方式，以便进行身份鉴别，这种技术已在医院身份鉴别等领域得到了应用。
Q: 金融卡能够替代哪两种卡？A: 信用卡和ATM卡2.2 短文听力5. 现在，许多任意信息被公开发布在网上，但只有少数人真正理解其中的意义。
信息丰富的世界并没有给人们的决策带来便利，相反，它令人们更加困惑。
因此，以责任为导向的新闻和应酬能够帮助大众理解所收集到的信息。
Q: 信息丰富的世界为什么令人们更加困惑？A: 信息过多，令人们难以作出决策。
二、阅读部分1.词汇选项6. Google著名的Web日历已经成为一个用户量极大的计划和时间管理工具。
这个日历最初只是为了在Google用户之间共享日程安排而建立的，但现在，它已成为最受欢迎的Web日历之一。
Google Web日历允许用户存储和共享诸如会议、生日、飞行时间、TV节目时间等事件；这个日历还可以与其他应用程序（例如Gmail和Google Earth）无缝集成。
全国计算机等级考试四级笔试试题一(上)
全国计算机等级考试四级笔试试题一（上）一、选择题。
(共90题,分为1分题和2分题,满分120分。
除标注2分题外,其它均为1分题。
）(1) 若或非门的输入变量为A和B,输出变量为Y,则A和B分别为下述哪一种情况时, Y 才为1?_____。
A) 1,0 B) 0,1 C) 0,0 D) 1,1(2) 已知寄存器A存有带符号整数且只作算术移位,HA和LA分别代表其最高位和最低位。
寄存器B存有带符号整数且只作逻辑移位,HB和LB分别代表其最高位和最低位。
当寄存器A与B都有左移位发生时,下述哪一个命题是正确的? _____。
(2分)A) LA与LB均成为0 B) LA与LB均成为1C) LA变成0但LB保持原值D) LA保持原值但LB的值改变(3) 下述哪一种情况称为指令周期?A) 取指令时间B) 取操作数时间C) 取指令和执行指令的时间D) 存储操作结果的时间(4) 设S是一个至少有两个元素的集合,且定义运算X*Y=X适用于S集中的所有元素X 和Y,下列命题中哪一个命题必是真命题?_____。
Ⅰ. *在S集中是可结合的Ⅱ. *在S集中是可交换的Ⅲ. *在S集中有单位元A) 只有ⅠB) 只有ⅡC) Ⅰ和ⅢD) Ⅱ和Ⅲ(5) 设Z是整数集,且设f:Z×Z→Z,对每一个∈Z×Z,有f()=m²n。
集合{0}的原象为_____。
(2分)A) {0}×ZB) Z×{0}C) ({0}×Z)∩(Z×{0})D) ({0}×Z)∪(Z×{0})(6) 对于一个只有3个不同元素的集合A来说,A上的等价关系的总数为_____。
A) 2 B) 5 C) 9 D) 取决于元素是否为数值(7) 设有命题:对于组成元素为集合的集合C,存在函数为f:C→∪C,使得对每一个S∈C,有f(S)∈S。
该命题的否命题是_____。
A) 对于集合C,对每个函数f:C→∪C,对每一个S∈C,都有f(S) ∈\ SB) 对于集合C,存在函数f:C→∪C,使对每一个S∈C,有f(S) ∈\ SC) 对于集合C,对每一个函数f:C→∪C,存在S∈C,使得f(S) ∈\ SD) 对于集合C,不存在函数f:C→∪C,使对某些S∈C,没有f(S) ∈\ S(8) 设(V,E)是一连通的无圈图,V包含3个3度顶点2个2度顶点r个1度顶点且V不再包含其他元素。
全国计算机等级四级机试试题及答案二(1-10)
全国计算机等级四级机试试题及答案二(1-10)1./* 程序PROG1.C的功能是：选出100至1000之间所有个位数字与十位数字之和被10除所得余数恰是百位数字的素数（如293）。
计算并输出上述这些素数的个数cnt以及这些素数值的和sum。
请考生编写函数countValue( )实现程序的要求，最后调用函数writeDAT( )把结果cnt和sum输出到文件out6.DAT中。
注意：部分源程序存放在PROG1.C中。
请勿改动主函数main( )和输出数据函数writeDAT( )的内容。
*/#includeint cnt, sum ;void countValue(){}void main(){cnt = sum = 0 ;countValue() ;printf("素数的个数=%d\n", cnt) ;printf("满足条件素数值的和=%d", sum) ;writeDAT() ;}writeDAT(){FILE *fp ;fp = fopen("OUT6.DAT", "w") ;fprintf(fp, "%d\n%d\n", cnt, sum) ;fclose(fp) ;}2. /* 编写函数sumValue( )，它的功能是：计算正整数n的所有因子(1和n除外)之和作为函数值返回。
例如：n=20时，函数值为21。
函数ReadWrite( )是实现从文件in9.dat中读取两个字符串，并调用函数sumValue()，最后把结果输出到文件out9.dat中。
注意：部分源程序存在文件PROG1.C中，请勿改动主函数main()和其它函数中的任何内容，仅在函数sumValue()的花括号中填入你编写的若干语句。
*/#include#includeint sumValue(int n){}main(){ clrscr() ;printf("%d\n", sumValue(20)) ;ReadWrite() ;}ReadWrite(){FILE *fp, *wf ;int i, n, s ;fp = fopen("in9.dat","r") ;if(fp == NULL) {printf("数据文件in9.dat不存在!") ;return ;}wf = fopen("out9.dat","w") ;for(i = 0 ; i < 10 ; i++) {fscanf(fp, "%d", &n) ;s = sumValue(n) ;fprintf(wf, "%d\n", s) ;}fclose(fp) ;fclose(wf) ;}3./* 请编写一个函数changeStr(char *s)，函数的功能是把s串中所有的字母改写成该字母的下一个字母，字母z改写成字母a。
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全国计算机等级考试四级笔试试题(2000年9月)(考试时间180分钟，满分100分)一、选择题:(共70题，每题1分，满分70分。
其中1-55题为中文题，56-70题为英文题)。
下列各题A)、B)、C)、D)四个选项中,只有一个是正确的,请将正确选项涂写在答题卡相应位置上,答在试卷上不得分。
(1) 计算机控制器的核心是A) 时序产生器B) 程序计数器C) 操作控制器D) 指令寄存器(2) 若一个子程序起始地址为2K，调用指令CALL的内存地址为K+2，则执行CALL指令所要执行指令的地址为A) 2K B) 2K+1 C) 2K-1 D) K+3(3) 2000年3月17日生效的标准GB18030-2000共收录汉字的数目为A) 6763个B) 7360个C) 17000个D) 27000个(4) 栈S最多能容纳4个元素。
现在6个元素按A、B、C、D、E、F的顺序进栈，下列哪一个序列不是可能的出栈序列？A) A、B、C、D、E、F B) A、F、E、D 、C、BC) C、B、E、D、A、F D) C、D、B、F、E、A(5) 由四个结点可以构造出多少种不同的二叉树？A) 4 B) 5 C) 14 D) 15(6) 下图所示为一棵二叉排序树，其存储采取llink-rlink法。
现要删除指针q所指的结点，下面哪一个操作序列不能得到正确的结果？A) q^.info:=q^.llink^.info；q^.llink:=nil；B) q^.info:=q^.rlink^.llink^.info；q^.rlink^.llink:=nil；C) p^·llink:=q^·llink；p^.llink^.rlink:=q^.rlink；D) p^.llink:=q^.rllink；p^.llink^.rlink:=q^.llink；(7) 设散列表的当前状态如下：A) 0.27 B) 0.42 C) 0.58 D) 0.73(8) 下面关于有向图的运算的叙述中，哪个（些）是正确的？Ⅰ. 求有向图结点的拓扑序列，其结果必定是唯一的Ⅱ. 求两个指向结点间的最短路径，其结果必定是唯一的Ⅲ. 求事件结点网络的关键路径，其结果必定是唯一的A) 只有ⅠB) Ⅰ和ⅡC) 都正确D) 都不正确(9) 下列命题公式中哪个（些）为重言式？Ⅰ. ((p∨q)→r┌) →((p→r)∧(q→r))Ⅱ. (p→(q∨r)) →((p→q )∧(p→r))Ⅲ. ((p→q)∧(p→r)) →((p→r)Ⅳ. ((p∨q)∧(p→r))←(p→r)A) ⅢB) Ⅰ和ⅢC) Ⅰ和ⅡD) Ⅰ、Ⅱ、Ⅲ和Ⅳ(10) 设A、B、C、D为任意的集合，下面命题中为假的是A) A-B=B当且仅当A=B=Ø∩⊆⋂⋃⊂ B) 若A⊂B∧C⊂D，则(A⋃C) ⊂ ( B⋃ D)C) 若A⊆B∧C⊂D，则(A⋃C) ⊆ ( B⋃ D) D) A-B=A⋂~B(11) 设f:Z×Z→Z,f(<n, k>)=n2k，其中Z为整数集合，下面哪些命题为真？Ⅰ. f是满射的Ⅱ. f是单射的Ⅲ. f-1(N)=Z×N(N为自然数集合)Ⅳ. f(z{1})=NA) Ⅰ和ⅡB) Ⅰ和ⅣC) Ⅰ和ⅢD) 全为真(12) 设N为自然数集合，<N,*> 在下面四种运算下不构成代数系统的是A) x*y=x+y-2-x-y B) x*y=x+y C) x*y=x-y D) x*y=|x|+|y|(13) 设七阶(即七个顶点)无向图G为k—正则图，下面列出k值中哪个（些）对于上述命题不成立？Ⅰ. k=4Ⅱ. k=5Ⅲ. k=6Ⅳ. k=7A) Ⅱ和ⅣB) 只有ⅣC) Ⅰ、Ⅱ和ⅣD) 全部(14) 下列命题中哪个一定为真？A) 若无向图G为极大平面图，则G的对偶图G`也是极大平面图B) G为非无向连通图当且仅当G的边连通度λ(G)=0C) 若能将无向图G的所有顶点排在G的同一个初级回路上，则G为哈密顿图D) 若G为n阶m条边r个面的平面图，则n-m +r=2工程所需的最长时间。
(15) 下列关于网络操作系统和分布式操作系统的叙述中，哪个是正确的Ⅰ. 它们都通过消息实现通信Ⅱ. 它们都运行相同的操作系统Ⅲ. 它们都有网络的支持A) 只有ⅠB) 只有ⅡC) 只有ⅢD) 都不正确(16) 当系统正在处理某一中断时，若要防止同级中断的干扰，可采取下列哪一种手段？A) 中断优先级B) 中断屏蔽C) 中断嵌套D) 中断响应(17) 下列关于进程控制块PCB的叙述中，哪些是正确的？Ⅰ. 系统利用PCB描述进程的基本静态特征Ⅱ. PCB可用于描述进程的运动变化过程Ⅲ. 一个进程唯一对应一个PCBA) Ⅰ和ⅡB) Ⅱ和ⅢC) Ⅰ和ⅢD) 全都正确(18) 在采用非抢占式进程调度方式下，下列哪一种情况不会引起进程切换？A) 一个更高优先级的进程就绪B) 时间片到C) 进程运行完毕D) 进程执行P操作(19) 在多道程序系统中，内存中既有操作系统，又有许多用户程序。
为使系统正确运行，要采取存储保护措施以防止Ⅰ.地址越界Ⅱ.操作越权A) 只有ⅠB) 只有ⅡC) Ⅰ和ⅢD) 都不正确(20) 在文件系统中，若要实现文件拷贝功能，可利用已有的系统调用，它们是A) create,open,read,write,closeB) create,open,read,write,deleteC) create,open,read,writeD) create,read,write,close(21) 在多道程序系统中，多个进程可对共享设备进行同时访问。
因此，在实现时应考虑下列哪些问题？Ⅰ. 正确性Ⅱ. 系统性能Ⅲ. 合理性A) Ⅰ和ⅡB) Ⅱ和ⅢC) Ⅰ和ⅢD) 都正确(22) 下列关于UNIX的叙述中，不正确的是A) UNIX的文件系统是树型结构的，便于管理和检索B) UNIX提供了丰富的软件工具，如实用程序、文本工具和开发工具C) UNIX把普通文件、目录文件和设备文件分别以不同方式进行管理D) UNIX是多用户、多任务的分时操作系统(23) 在UNIX系统中，组成UNIX执行环境的是一系列A) 环境变量B) 管道C) 特殊文件D) 管理命令(24) 软件开发的结构化生命周期方法将软件生命周期划分成A) 计划阶段、开发阶段、运行阶段B) 计划阶段、编程阶段、测试阶段C) 总体设计、详细设计、编程调试D) 需求分析、功能定义、系统设计(25) 数据流图是常用的进行软件需求分析的图形工具，其基本图形符号是A) 输入、输出、外部实体和加工B) 变换、加工、数据流和存储C) 加工、数据流、数据存储和外部实体D) 变换、数据存储、加工和数据流(26) 判定表和判定树是数据流图中用以描述加工的工具，它常描述的对象是A) 逻辑判断B) 层次分解C) 操作条目D) 组合条件(27) 模块独立性是软件模块化所提出的要求，衡量模块独立性的度量标准则是模块的A) 抽象和住处隐蔽B) 局部化和封装化C) 内聚性和耦合性D) 激活机制和控制方法(28) 软件设计一般分为总体设计和详细设计，它们之间的关系是A) 全局和局部B) 抽象和具体C) 总体和层次D) 功能和结构(29) 软件的复审是保证软件质量的必要手段，下述Ⅰ.软件的可追溯性Ⅱ.软件的可维护性Ⅲ.方案的可选择性Ⅳ.接口的明确性哪些是软件复审时所涉及的技术内容？A) Ⅰ和ⅡB) Ⅰ、Ⅱ和ⅢC) Ⅱ和ⅢD) 都正确(30) 原型化方法是软件开发中一类常用的方法，它与结构化方法相比较，更需要A) 明确的需求定义B) 完整的生命周期C) 较长的开发时间D) 熟练的开发人员(31) 软件测试是软件开发的重要环节，而进行软件测试的目的是A) 证明软件错误不存在B) 证明软件错误的存在C) 改正程序所有的错误D) 发现程序所有的错误(32) 软件维护是保证软件正常、有效运行的重要手段，而软件的下述特性：Ⅰ.可测试性Ⅱ.可理解性Ⅲ.可修改性Ⅳ.可移植性哪个（些）有利于软件的维护？A) 只有ⅠB) Ⅱ和ⅢC) Ⅰ、Ⅱ和ⅢD) 都有利(33) 数据库的三级模式结构由外模式、模式和内模式组成，它适合于哪个（些）类型的数据库？Ⅰ. 关系型数据库Ⅱ. 层次型数据库Ⅲ. 网状型数据库A) 只有ⅠB) Ⅰ和ⅡC) Ⅱ和ⅢD) 都适合(34) 设关系R和关系S的元素分别是3和4，关系T是R与S的笛卡尔积，即：T=R>×S，则关系T的元数是A) 7 B) 9 C) 12 D) 16(35) 在SQL语言中的表(Table)是数据库的A) 内模式B) 模式C) 外模式D) 概念模式(36) 设有关系R和S，在下列的关系运算中，哪一种运算不要求：“R和S具有相同的元数，且它们对应属性的数据类型也相同”？A) R⋃S B) R∩S C) R－S D) R×S(37) 设有关系R(A,B,C,D)，其函数依赖集F={A→B,A→C,BD}，则关系R至多满足A) 1NF B) 2NF C) 3NF D) BCNF(38) 设有关系R(A,B,C)，在下列的等式中，哪一个是不成立的？A) σA<2(πA, B(R))=πA, B(σA<2 (R))B) πA, C(σA<2(R))=σA<2(πA, C(R))C) πB, C(σA<2(R))=σA<2(πB,C(R))D) πA(πA, B (R))=π A (R)(39) 关系数据模型通常由三部分组成，它们是A) 数据结构，数据通信，关系操作B) 数据结构，关系操作，完整性约束C) 数据通信，关系操作，完整性约束D) 数据结构，数据通信，完整性约束(40) 在关系数据库设计中，对关系进行规范化处理，使关系达到一定的范式，例如达到3NF，这是哪个设计阶段的内容？A) 需求分析阶段B) 概念设计阶段C) 逻辑设计阶段D) 物理设计阶段(41) 如果有两个事务，同时对数据库中同一数据进行操作，不会引起冲突的操作是A) 其中有一个是DELETEB) 一个是SELECT，另一个是UPDATEC) 两个都是SELECTD) 两个都是UPDA TE(42) 通过计算机某些部分的改进而获得的性能增益可以用阿姆达尔定律计算出来，该定律指出：利用更快的执行方式而获得的性能改善所受到的限制是A) 该方式所占的空间大小B) 该方式所占的时间比例C) 该方式所占的芯片多少D) 该方式所占的流水位置(43) 计算机体系结构的一个重要区别是CPU内部的存储类型，就是说从存储器取来操作数后把它暂存在什么地方。
在微型机中采用的暂存机制是A) 堆栈与累加器B) 堆栈与寄存器集C) 累加器集D) 累加器与通用寄存器(44) 在指令编码优化过程中，哈夫曼编码的核心思想是A) 使用频率高的指令用短码表示B) 使用频率高的指令用长码表示C) 使用频率高的指令用理论码表示D) 使用频率高的指令用等长码表示(45) RISC的关键技术是寄存器窗口重叠技术，这项技术很好地支持过程调用和返回操作。