问题 选择题

关于曲线运动,有下列说法,其中正确的是(  )

A.曲线运动一定是变速运动

B.曲线运动一定是匀速运动

C.在平衡力作用下,物体可以做曲线运动

D.在恒力作用下,物体不可以做曲线运动

答案

A、曲线运动的条件,合外力与速度不在一条直线上,速度方向时刻变化,故曲线运动是变速运动,故A正确,B错误.

C、曲线运动合力一定不能为零,故C错误.

D、在恒力作用下,物体可以做曲线运动,故平抛运动,故D错误.

故选:A

完形填空

Hidden passengers traveling in ships, trams, or even cars can be a terrible trouble— especially when they are insects. As for this, there is a great ___36___ between human beings; and insects. The former ___37___ every possible effort to avoid being discovered, while the latter quickly ___38___ attention to themselves.

We can only show mercy to the ___39___ man who had to slop his car soon after ___40___ from a country village to drive to London. Hearing a strange noise from the ___41___of the car, he naturally got out to ___42___ the wheels carefully, but he found nothing wrong, so he ___43___ his way. Again the noise began, ___44___ and became even louder. Quickly ___45___ his head, the man saw what appeared to be a great ___46___ cloud following the car. When he stopped at a village further on, he was told that a queen bee must be hidden in his car as there were thousands of bees ___47___.

On learning this, the man drove away .as quickly as possible. After an hour’s ___48___ driving, he arrived safely in London, where he parked his car outside a ___49___ and went in- It was not long ___50___ a customer who had seen him arrive ___51___ in to inform him that his car was ___52___ with bees. The poor driver was ___53___ that the best way should be to call a ___54___. In a short time the man arrived. He found the unwelcome passenger hidden near the wheels at the back. of the car. Very thankful to the driver for this ___55___ gift, the bee-keeper took the queen and her thousand of followers home in a large box.

36. A. connection   B. difference  C. communication D. similarity

37. A, doB. take   C. make D. try

38. A. give     B. keep     C. pay      D. draw

39. A. unfortunate  B. careless     C. unpleasant D. hopeless

40. A. passing by   B. leaving out   C. setting out    D. getting up

41. A. front    B. back     C. left      D. right

42. A. clean    B. change      C. test      D. examine

43. A. drove   B. continued C. pushed    D. forced

44. A. normally     B. gentlyC. actually     D. immediately

45. A. hiding  B. turning      C. shaking     D. raising

46. A. black    B. beautiful   C. white D. colorful

47. A. below   B. ahead C. nearby      D. behind

48. A. boring  B. careful      C. exciting     D. hard

49. A. hotel    B. museum    C. hospital     D. school

50. A. when    B. after  C. until  D. before

51. A. broke   B. moved      C. hurried      D. dropped

52. A. crowded      B. covered     C. filled D. equipped

53. A. advised B. required    C. ordered     D. requested

54. A. bee-keeper B. policeman    C. waiterD. repairman

55. A. unfamiliar   B. unknown   C. unexpectedD. uncertain

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