31. Only after the bus________for a few miles did Jane realize she was on the wrong route.

                                           A. was running              B. had run                      C. has run          D. runs

32. The children________to bed before their parents came home from work.

A. were all going                B. had all gone              C. had all been going     D. have all gone

33. Paul noticed a job advertisement while he________along the street.

                                           A. was walking              B. would walk               C. walked          D. had walked

34. I haven’t met him again since we________school ten years ago.A. have left       B. leave           C. left  D. had left

35. For the last 20 years, we________significant changes in the world of science and technology.

                                           A. witness                      B. have witnessed          C. witnessed      D. are witnessing

36. My best friend Lan________to England 10 years ago.A. was moving    B. moves           C. moved         D. has moved

37. Mr.Pike________for this company for more than thirty years, and he intends to stay here until he________.

A. worked/retires                B. works/is retiring        C. has been working/retires         D. is working/will retire

38. While I________at the bus stop, three buses went by in the opposite direction.

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

39. By the end of last March, I________English for five years.A. had been studied              B. had been studying

                                           C. will have been studying                                  D. will have studied

40. ________Alan for hours but he hasn’t answered his mobile. I hope nothing’s wrong.

                                           A. I call                         B. I’ve been calling        C. I’m calling     D. called