41. We________in silence when he suddenly________me to help him.A. walked - was asking        B. were walking - asked

                                           C. were walking - was asking                              D. walked - asked

42. By the time the software________on sale next month, the company________$2 million on developing it.

A. went - had spent            B. will go - has spent     C. has gone - will spend D. goes - will have spent

43. When Carol________last night, I________my favorite show on television.

A. called /was watching      B. had called /watched  C. called /have watched D. was calling /watched

44. Linda took great photos of butterflies while she_______in the forest.A. was hikingB. is hiking C. hikedD. had hiked

45. When I________for my sister in front of the supermarket, a strange man came to talk with me.

                                           A. was waiting               B. waited                       C. had waited    D. were waiting

46. Over the past 30 years, the average robot price________by half in real terms, and even further relative to labor costs.

                                           A. is fallen                     B. has fallen                  C. were fallen    D. have fallen

47. When I came to visit her last night, she________abath.A. is havingB. was having           C. has had        D. had had

48. John________in the same house since he left school.A. livedB. had lived           C. was living    D. has lived

49. Since Tom________, I have heard nothing from him.A. had left            B. left    C. has left        D. was left

50. He will take the dog out for a walk as soon as he _______ dinner.A. finish         B. has finished C. will finish    D. finished