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簡述焊接電弧靜特性曲線的意義。

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試題分類: 資料員
練習次數:0次
What does the future hold for the problem of housing? A good deal depends, of course, on the meaning of “future”. If one is thinking in terms of science fiction and the space age, it is at least possible to assume that man will have solved such trivial and earthly problems as housing. Writers of science fiction, from H.G. Wells onwards, have had little to say on the subject. They have conveyed the suggestion that men will live in great comfort, with every conceivable apparatus to make life smooth, healthy and easy, if not happy. But they have not said what his house will be made of. Perhaps some new building material, as yet unimagined, will have been discovered or invented at least. One may be certain that bricks and mortar(泥灰,灰漿) will long have gone out of fashion. But the problems of the next generation or two can more readily be imagined. Scientists have already pointed out that unless something is done either to restrict the world’s rapid growth in population or to discover and develop new sources of food (or both), millions of people will be dying of starvation or at the best suffering from underfeeding before this century is out. But nobody has yet worked out any plan for housing these growing populations. Admittedly the worst situations will occur in the hottest parts of the world, where housing can be light structure or in backward areas where standards are traditionally low. But even the minimum shelter requires materials of some kind and in the teeming, bulging towns the low-standard “housing” of flattened petrol cans and dirty canvas is far more wasteful of ground space than can be tolerated. Since the war, Hong Kong has suffered the kind of crisis which is likely to arise in many other places during the next generation. Literally millions of refugees arrived to swell the already growing population and emergency steps had to be taken rapidly to prevent squalor(骯臟)and disease and the spread crime. The city is tackling the situation energetically and enormous blocks of tenements(貧民住宅)are rising at an astonishing aped. But Hong Kong is only one small part of what will certainly become a vast problem and not merely a housing problem, because when population grows at this rate there are accompanying problems of education, transport, hospital services, drainage, water supply and so on. Not every area may give the same resources as Hong Kong to draw upon and the search for quicker and cheaper methods of construction must never cease. 1.What is the author’s opinion of housing problems in the first paragraph? A.They may be completely solved at sometime in the future. B.They are unimportant and easily dealt with. C.They will not be solved until a new building material has been discovered. D.They have been dealt with in specific detail in books describing the future. 2.The writer is sure that in the distant future ___. A.bricks and mortar will be replaced by some other building material. B.a new building material will have been invented. C.bricks and mortar will not be used by people who want their house to be fashionable. D.a new way of using bricks and mortar will have been discovered. 3.The writer believes that the biggest problem likely to confront the world before the end of the century ___. A.is difficult to foresee. B.will be how to feed the ever growing population. C.will be how to provide enough houses in the hottest parts of the world. D.is the question of finding enough ground space. 4.When the writer says that the worst situations will occur in the hottest parts of the world or in backward areas, he is referring to the fact that in these parts ___. A.standards of building are low. B.only minimum shelter will be possible. C.there is not enough ground space. D.the population growth will be the greatest. 5.Which of the following sentences best summarizes Paragraph 3? A.Hong Kong has faced a serious crisis caused by millions of refugees. B.Hong Kong has successfully dealt with the emergency caused by millions of refugees. C.Hong Kong’s crisis was not only a matter of housing but included a number of other problems of population growth. D.Many parts of the world may have to face the kind of problems encountered by Hong Kong and may find it much harder to deal with them.
試題分類: 大學英語六級
練習次數:1次
Scattered through the seas of the world are billions of tons of small plants and animals called plankton. Most of these plants and animals are too small for the human eye to see. They drift about lazily with the currents, providing a basic food for many larger animals. Plankton has been described as the equivalent of the grasses that grow on the dry land continents, and the comparison is an appropriate one. In potential food value however, plankton far outweighs that of the land grasses. One scientist has estimated that while grasses of the world produce about 49 billion tons of valuable carbohydrates each year. The sea’s plankton generates more than twice as much. Despite its enormous food potential, little effort was made until recently to farm plankton as we farm grasses on land. Now marine scientists have at last begun to study this possibility, especially as the sea’s resources loom even more important as a means of feeding an expanding world population. No one yet has seriously suggested that “planktonburgers” may soon become popular around the world. As a possible farmed supplementary food source, however, plankton is gaining considerable interest among marine scientists. One type of plankton that seems to have great harvest possibilities is a tiny shrimplike creature called krill. Growing to two or three inches long, krill provide the major food for the giant blue whale, the largest animal ever to inhabit the Earth. Realizing that this whale may grow 100 feet and weigh 150 tons at maturity, it is not surprising that each one devours more than one ton of krill daily. Krill swim about just below the surface in huge schools sometimes miles wide, mainly in the cold Antarctic. Because of their pink color, they often appear as a solid reddish mass when viewed from a ship or from the air. Krill are very high in food value. A pound of these crustaceans contains about 460 calories—about the same as shrimp or lobster, to which they are related. If the krill can feed such huge creatures as whales, many scientists reason, they must certainly be contenders as new food source for humans. 1.Which of the following best portrays the organization of the passage? A.The author presents the advantages and disadvantages of plankton as a food source. B.The author quotes public opinion to support the argument for farming plankton. C.The author classifies the different food sources according to amount of carbohydrate. D.The author makes a general statement about plankton as a food source and then moves to a specific example. 2.According to the passage, why is plankton regarded to be more valuable than land grasses? A.It is easier to cultivate. B.It produces more carbohydrates. C.It does not require soil. D.It is more palatable. 3.Why does the author mention “planktonburgers”? A.To describe the appearance of one type of plankton. B.To illustrate how much plankton a whale consumes. C.To suggest plankton as a possible food sources. D.To compare the food values of beef and plankton. 4.What is mentioned as one conspicuous feature of krill? A.They are the smallest marine animals. B.They are pink in color. C.They are similar in size to lobsters. D.They have grass like bodies. 5.The author mentions all of the following as reasons why plankton could be considered a human food source except that it is ___. A.high in food value. B.in abundant supply in the oceans. C.an appropriate food for other animals. D.free of chemicals and pollutants.
試題分類: 大學英語六級
練習次數:1次
Part II Vocabulary and Structure Directions: In this part there are forty incomplete sentences. Each sentence is followed by four choices. Choose the one that best completes the sentence and then mark your answer on the Answer Sheet. 21. The teacher the students on a tour through the art museum. A. made B. indicated C. forced D. took 22. Tom’s parents died when he was a child, so he was by his relatives. A. grown up B. brought up C. raised D. fed up 23. Here is my card. Let’s keep in . A. touch B. relation C. connection D. friendship 24. So far there is no proof people from other planets do exist. A. which B. how C. what D. that 25. The newspapers reported yesterday several on the boundaries of these two countries. A. incidents B. happenings C. events D. accidents 26. We’ve worked out the plan and now we must put it into . A. fact B. reality C. practice D. deed 27. He didn’t and so he failed the examination. A. work enough hard B. hard work enough C. hard enough work D. work hard enough 28. Not until Mr. Smith came to China what kind of country she is. A. he knew B. he didn’t know C. did he know D. he couldn’t know 29. Scientists say it may be ten years this medicine was put to use. A. since B. before C. after D. when 30. In some countries, is called “equality” does not really mean equal rights for all people. A. that B. what C. which D. how 31. We didn’t know his telephone number, otherwise we him. A. would telephone B. would have telephone C. had telephoned D. must have telephoned 32. We’ve missed the last bus, I’m afraid we have no but to take a taxi. A. way B. possibility C. choice D. selection 33. Luckily, most sheep the flood last month. A. endured B. survived C. lived D. passed 34. My parents always let me have my own of living. A. way B. method C. manner D. fashion 35. Like other language skills, reading requires practice. A. the most of B. much of the C. most of the D. more of the 36. It is only through practice one will be able to swim skillfully. A. what B. who C. that D. which 37. The brain is capable of ignoring pain message of to concentrate on other activities. A. it allowed B. is it allowed C. allowed D. allowed it 38. Don’t worry, I have already them the decision. A. informed; with B. informed; of C. informed; for D. informed; that 39. The child was sorry his mother when he arrived at the station. A. to miss B. having missed C. missing D. to have missed 40. I wonder why he to discuss the problem at the meeting. A. declined B. rejected C. refused D. delayed 41. You can hang up what you like on these walls. A. bare B. empty C. blank D. vacant 42. According to a , the majority would rather have newspapers without a government than a government without newspapers. A. election B. campaign C. poll D. vote 43. The population of the village has decreased 150 to 500. A. in B. at C. by D. with 44. It seems that there is that I can’t do. A. nothing B. anything C. everything D. none 45. They are often caring more about animals than human beings. A. accused if B. accused with C. charged of D. charged for 46. a good beginning is made, the word is half done. A. As soon as B. While C. As D. Once 47. George could not his foolish mistake. A. account in B. count on C. count for D. account for 48. We came into this field late, so we must work hard to the lost time. A. make up for B. make out C. keep up with D. put up with 49. The new law will came into on the day it is passed. A. effect B. use C. service D. existence 50. We can separate the mixture into the pure chemical compounds it is composed. A. in which B. of what C. of which D. from which 51. Mrs. Lincoln has that she is unable to get a job. A. such small education B. so little education C. a such little education D. a so small education 52. She can’t prevent her little boy shooting birds. A. from; to B. on; at C. with; up D. from; at 53. Many countries are increasing their use of natural gas, wind and other forms of . A. energy B. source C. power D. material 54. A darkened sky in the daytime is usually and indication that a storm is . A. possible coming B. about to take place C. close by D. expected to be severe 55. We all know that speak louder than words. A. movements B. performance C. operations D. actions 56. , he could not cover the whole distance in fifteen minutes. A. Fast as he can B. As he can ran fast C. If he can ran fast D. Since he ran fast 57. Agricultural production in that country has increased in recent years. A. vastly B. strikingly C. considerably D. extremely 58. Peter has planned to some money every month so that he can buy a used car next year. A. set aside B. set up C. set in D. set along 59. Although I spoke to him many times, he never took any of what I said. A. attention B. notice C. warning D. observation 60. They overcame all the difficulties and fulfilled the plan three months ahead of time, is something we had not expected. A. that B. what C. it D. which
試題分類: 大學英語四級
練習次數:3次
The food we eat seems to have profound effects on our health. Although science has made enormous steps in making food more fit to eat, it has , atthe same time, made many foods unfit to eat. Some research has shown that perhaps eighty percent of cancer is related to the diet as well, especially cancer the colon . Different cultures are more prone to contract certain illnesses because of the food that is characteristic in these cultures. That food related to llness is not a new discovery. In 1945 , government researchers realized that itrates and nitrites, commonly used to preserve color in meats, and other food dditives, caused cancer. Yet, these carcinogenic additives remain in our food, nd it becomes more difficult all the time to know which things on the pack ging labels of processed food are helpful or harmful.The additives which we eat are not all so direct. Farmers often give penicillin to beef and poultry, and because of this, penicillin has been found in the milk of treated cows. Sometimes similar drugs are administered to animals not for medicinal purposes, but for financial reasons. The farmers are simply trying to fatten the animals in order to obtain a higher price on the market. Although the Food and Drug Administration (FDA) has tried repeatedly to controlthese procedures, the practices continue. 48. What is the main topic of the passage? A. Food and our health B Food and additives C. Food and cancer D Food and culture 49 All of the following statements are true EXCEPT_______. A Forty percent of cancer is caused by problems related to food. B Researchers have known about the potential danger of food additivesfor many years C. We eat some of the food additives directly and some indirectly D Drugs are always given to animals for medicinal purposes 50. Why do farmers give drugs to their animals? A. to speed up the growth of animals B To make theanimals fatter C to make the animals ’ meat fit to eat D To make the animals’ meat rich in nutrients 51. It can be inferred from the passage that_________. A scientist have made all the food fit to eat B only in recent years have people found that the food is related to one’s illness C all kinds of cancer are related to the diet D some additives are harmful to our health 52. The word “ this ”in the second sentence of paragraph 2 most probablyrefers to __________. A farmer B penicillin C beef and poultry D the fact that farmers often give penicillin to a beef
試題分類: 大學英語三級
練習次數:4次
Directions: In this section, there are 10 incomplete sentences. You are required to complete each one by deciding on the most appropriate word or words from the 4 choices marked A, B, C and D. Then you should mark the corresponding letter on the Answer Sheet with a single line through the center. 21、 62% of the people surveyed said they always avoided ______ theirsmartphones during meals. A. use B. using C. to use D. used 22、 The HR department is a critical part of employee well-being in any business, no matter ______ small it is. A. how B. what C. where D. which 23、 According to the regulation, inspections______ to ensure that the systems are in good condition. A. demanded B. have demanded C. be demanded D. are demanded 24、 Before you think about asking for a promotion, make sure that either a position opening exists ______ a new position is needed to be created. A. and B. nor C. or D. but 25、 The traffic was making so much noise that I couldn't hear what he ______. A. is saying B. was saying C. has said D. will say 26、 Our company culture is ______ makes us successful in creating a friendly and exciting environment. A. where B. how C. what D. why 27、 Most people were greatly shocked by the news ______ the IT company had gone bankrupt. A. what B. how C. why D. that 28、 I would probably try to find a better job if I ______ in your position. A. am B. were C. have been D. be 29、 If you are ______ busy to attend the meeting, you can send your assistant to take your place. A. very B. so C. too D. more 30、 I had to wait for another two months to be able to have the car ______. A. fixing B. fix C. to fix D. fixed
試題分類: 大學英語三級
練習次數:8次
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