1.

图5－3－15

如图5－3－15所示，质量相等的甲、乙两小球从一光滑直角斜面的顶端同时由静止释放，甲小球沿斜面下滑经过a点，乙小球竖直下落经过b点，a、b两点在同一水平面上，不计空气阻力，下列说法中正确的是(　)

A．甲小球在a点的速率等于乙小球在b点的速率

B．甲小球到达a点的时间等于乙小球到达b点的时间

C．甲小球在a点的机械能等于乙小球在b点的机械能(相对同一个零势能参考面)

D．甲小球在a点时重力的功率等于乙小球在b点时重力的功率

解析：由机械能守恒得两小球到达a、b两处的速度大小相等，A、C正确；设斜面的倾角为α，甲小球在斜面上运动的加速度为a＝gsin α，乙小球下落的加速度为a＝g，由t＝可知t_甲＞t_乙，B错误；甲小球在a点时重力的功率P_甲＝mgvsin α，乙小球在b点时重力的功率P_乙＝mgv，D错误．

答案：AC

56. In the meantime, the question facing business is whether such research is ____ the costs. A. worth　　 B. worth of　　 C. worthy　　 D. worthwhile 57. The _____ runner can run 2 miles in fifteen minutes. A. common　　 B. usual　 C. average　　 D. general 58. David likes country life and has decided to ______ farming. A. go in for　　 B. go back on　　 C. go through with　　　 D. go along with 59. We should be able to do the job for you quickly, ____ you give us all the necessary information. A. in case　　　 B. provided that　　 C. or else　　 D. as if 60. The detective and his assistant have begun to ____ the mysterious murder. A. look into　　 B. see to　　 C. make over　　 D. come through

1-5　 CAADC　　　 6-10　 BBDAC　　 11-15 BCADA　　　 16-20ADDDB　　 21-25DBBAA　　　 26-30BDBCC　　 31-35 ABCBC　　　 36-40 ABCDD 41-45 CDCDB　　　 46-50 DCBCB　　 51-55 DDDAD　　　 56-60 ACABA

51. _____ I admit that there are problems, I don't' think that they cannot be solved. A. Unless　　 B. Until　　 C. As　　　 D. While 52. The place is an ideal site for a university ______ it is far from the downtown area. A. provided that　　 B. now that　　　 C. so that　　 D. in that 53. He thought he could talk Mr. Robinson _____ buying some expensive equipment. A. on　　 B. of　　 C. round　　 D. into 54. Today the public is much concerned about the way ____. A. nature is being ruined　　 B. which nature is ruined C. on which to ruin nature　　 D. of nature to be ruined 55. When I said goodbye to her, she _____ the door. A. saw me at　　 B. set me off　　 C. sent me to　　 D. showed me to

46. Rebecca______ me earlier if she did not like her house she bought last month. A. told　　 B. would tell　　 C. had told　 D. would have told 47. The world's greatest sporting event, the Olympic Games, upholds the amateur that _____ matters is not winning but participating. A. anything　　 B. it　　　 C. what　　 D. everything 48. It has been estimated(估计) that the earth's surface temperature has increased _____ sone quarter to three quarters of a degree since 1850. A. to　　 B. by　　　 C. at　　 D. with 49. Iceland lies far north in the Atlantic, with its northern most tip actually ____ the Arctic Circle(北极圈). A. touched　　 B. touches　　　 C. touching　　　 D. being touched 50. Colin married my sister and I married his brother, _____ makes Colin and me double in-laws. A. what　　 B. which　　 C. that　　　 D. it

41. One of the requirements for a fire is that the material ____ to its burning temperature. A. is heated　　 B. will be heated　　 C. be heated　　 D. would be heated 42. Why this otherwise excellent newspaper allows such an article to be printed is ___ me. A. above　　 B. outside　　 C. beside　　 D. beyond 43. This book will show the readers ___ can be used in other contexts. A. how that they have observed　　　 B. that how they have observed　 C. how what they have observed　　　 D. that they have observed 44. _____ your opinions are worth considering, the committee finds it unwise to place too much importance on them. A. As　　 B. Since　　 C. Provided　　 D. While 45. _____ the claim about German economic might, it is somewhat surprising how relatively small the German economy actually is. A. To give　　 B. Given　　 C. Giving　　　 D. Having given

36. As I'll be away for at least a year, I'd appreciate ____ from you now and thentelling me how everyone is getting along. A hearing　　 B. to hear　　 C. to be hearing　　 D. having heard 37. Greatly agitated(激动的), I rushed to the apartment and tried the, ____ to find it locked. A. just　　 B. only　　 C. hence　　 D. thus 38. If I were in a movie, then it would be about time that I ___ my head in my hands for a cry. A. bury　　 B. am burying　　 C. buried　 D. would bury 39. According to one belief, if truth is to be known it will make itself apparent, so one ____ wait instead of searching for it. A. would rather　　 B. had to　 C. cannot but　　 D. had best 40. So involved with their computers _____ that leaders at summer computer camps often have to force them to break for sports and games. A. became the children　　 B. become the children　 C. had the children become　 D. do the children become

31. _____ for the timely investment from the general public, our company would not be so thriving(兴旺的) as it is. A. Had it not been　　　 B. Were it not　　 C. Be it not　　 D. Should it not be 32. There were many people present and he appeared only for a few seconds, so I only caught a _____ of him. A. glance　　 B. glimpse　　 C. look　　 D. sight 33. I'm very glad to know that my boss has generously agreed to _____ my debt in return for certain services. A. take away　　 B. cut out　　 C. write off　　 D. clear up 34. Smoking is so harmful to personal health that it kills ___ people each year than automobile accidents. A. seven more times　　 B. seven times more　　 C. over seven times　　 D. seven times 35. This is an exciting area of study, and one ____ which new applications are being discovered almost daily. A. from　 B. by　 C. in　　 D. through

26. I worked so late in the office last night that I hardly had time ____ the last bus. A. to have caught　　 B. to catch　　 C. catching　　 D. having caught 27. As it turned out to be a small house party, we ____ so formally(正式地). A. needn't dress up　　　 B. did not need have dressed up　 C. did not need dress up　　 D. needn't have dressed up 28. I apologize if I ____ you, but I assure you it was unintentional(无意的). A. offend(冒犯)　　　 B. had offended　　 C. should have offended　 D. might have offended. 29. Marlin is a young man of independent thinking who is not about ____ compliments to his political leaders. A. paying　　 B. having paid　 C. to pay　　 D. to have paid　　　 30. Although a teenager, Fred could resist _____ what to do and what not to do. A. to be told　　 B. having been told　 C. being told　　 D. to have been told

21. Christmas is a Christian holy day usually celebrated on December 25th ____ the birth of Jesus Christ. A. in accordance with　　 B. in terms of　　 C. in favor of　　 D. in honor of 22. The Social Security Retirement Program is made up of two trust funds(基金,资金), ____could go penniless by next year. A. the larger one　　 B. the larger of which　　 C. the largest one　　 D. the largest of which 23. I would have gone to visit him in the hospital had it been at all possible, but I ____ fully occupied the whole of last week. A. were　　 B. had been　　 C. have been　　 D. was 24. When workers are organized in trade unions, employers find it hard to lay them _____. A. off　　 B. aside　　 C. out　　 D. down 25. I can't _____ what has happened to the vegetables, for they were freshly picked this morning. A. figure out　　 B. draw out　　 C. look out　　 D. work out.

16. Do you enjoy listening to records? I find records are often ____ or better than an actual performance. A. as good as　　 B. as good　　 C. good　　 D. good as 17. The article opens and closes with descriptions of two news reports, each _____ one major point in contrast with (和……相比) the other. A. makes　　 B. made　　 C. is to make　　 D. making 18. The number of registered participants in this year's marathon was half _____. A. of last year's　　　 B. those of last year's　　 C. of those of last year.　 D. that of last year's 19. I was speaking to Ann on the phone when suddenly we were _____. A. hung up　　 B. hung back　　 C. cut down　　 D. cut off 20. She wondered if she could have the opportunity to spend ____ here so that she could learn more about the city. A. sometimes　　 B. some time　　 C. sometime　　 D. some times.