50. 　 It is certain that men will never stop ______ new energy sources to power their growing industry.

A. finding　　 B. to find　　 C. having found　　 D. found

49. 　 The machines are made ______ at full speed.

A. work　　 B. working　　 C. to work　　 D. to be worked

48. 　 You’d better ______.

A. to have your shoes mended　　 B. to have mended your shoes

C. have your shoes mended　　　 D. having your shoes mended

47. 　 While she was shopping, she kept ______ the list to make sure she hadn’t forgotten anything.

A. checked　　 B. checking　　 C. to check　　 D. check

46. 　 The young man who saw the car ______ into the river telephoned the police station.

A. plunge　　 B. plunged　　 C. was plunging　　 D. to plunge

45. 　 In some countries there are already a number of firms ______ computer programming.

A. specialize in　　 B. specialized in　　 C. specializing in　　 　D. specializes in

44. 　 He felt bad for ______ a chance to study abroad.

A. having not given　　　 B. not having given

C. having not been given　 D. not having been given

43. 　 From the electric refrigerator Dick takes a carton of cream, another of fresh milk and a can of ______ orange juice.

A.　　　 frozen　　 B. froze　　 C. freezing　　 D. freezed

42. 　 Uncle Dick has already arrive. Do you expect ______ to see him?

A.　　　 Going　　 B. go　　 C. to go　　 D. that you go

41. 　 “Was the rally successful?’

“No, because the number of ______ was smaller than we had expected.”

A. people who attend　　 B. attended people　

C. people attending　　 D. attendance of people