16. They will go home for winter vacation as soon as they ______ their exams.

　　A. have finished B. finish C. will finish D. will have finished

　　17. About the sixth century A.D. when they few Europeans could read, the Chinese _____ paper.

　　A. invented B. had invented C. have invented D. had been invented

　　18. I fell and hurt myself while I ______ tennis.

　　A. was playing B. am playing C. play D. played

　　19. I _______ on the door for ten minutes now without an answer.

　　A. was knocking B. an knocking C. knocking D. have been knocking

　　20. When you _____ this over with herm you should not see her any more.

　　A. talk B. talked C. will talk D. talking

　　21. I ______ writing the article by the time you get back.

　　A. shall finish B. must have finished C. have finished D. shall have finished

　　22. No one can possible recall any detail about the meeting. It is at least five years since it ______.

　　A. had taken place B. was taken place C. tool place D. was taking place

　　23. “When are you going to visit your uncle in Chicago?”

　　“As soon as ______ our work for tomorrow.

　　A. we’re complete B. we’d complete C. we’ll complete D. we complete

　　24. When I went to visit Mrs. Smith last week, I was told she _____ two days before.

　　A. has left B. was leaving C. would leave D. had left

　　25. By the year he _____ in New York for five years.

　　A. has worked B. has been working C. works D. will have worked

　　26. By the time you arrive this evening, ______ for two hours.

　　A. I will study B. I will have studied C. I had studied D. I will have been studying

　　参考答案：

　　16-20 BBADB 21-25 DCDDD 26. D