16. The teacher told the students that the Earth_______round the Sun.

　　A. moves B. moved

　　C. has moved D. has been moving

　　17. While the secretary_______ his desk, he found the long lost report.

　　A. had been cleaning B. is cleaning

　　C. has been cleaning D. was cleaning

　　18. As soon as he______ his error, Rockfeller made the necessary corrections to his data collected.

　　A. discovered B. has discovered

　　C. discovers D. had discovered

　　19. Fred believed that his friend_______ by his employer a month or so ago.

　　A. had been promoted B. has been promoted

　　C. has promoted D. had promoted

　　20. I think I'll wait until the mail______ .

　　A. should come B. is coming

　　C. comes D. will come

　　21. We could have bought a new car last year ,but we really____ it.

　　A. can't afford B. couldn't afford

　　C. won't afford D. unable to afford

　　22. If you don't pay your taxes ,they______.

　　A. have you arrested B. will have you arrested

　　C. must have you arrested D. have you arrest

　　23. I _______meeting you ever since we parted.

　　A. was looking forward to B. have been looking forward to

　　C. had been looking forward to D. looked forward to

　　24. Mary ____in the garden when it began to rain.

　　A. was walking B .walked

　　C. walking D. had walked

　　25.Where have you been? What _____ ?

　　A. did you do B. have you been doing

　　C. have made D. were you doing

　　26.The boy couldn’t go to sleep because he _____ too long.

　　A. was talking B. talked

　　C. would talk D. had been talking

　　27. She has been studying here for five years and by the end of next summer she _____.

　　A. will graduate B. will be graduating

　　C. will be graduated D. will have graduated

　　28. By the end of 1976, we _____ the demand for petroleum.

　　A. met B. have met

　　C. had met D. had been meeting

　　29. When you come tonight at eight o’clock, I _____ eight lessons.

　　A. would review B. shall review

　　C. shall have reviewed D. shall be reviewing

　　30. Make sure that the doors _____ before you go out.

　　A. locked B. are loked

　　C. will locked D. lock