20. ---Guess what! I have got A for my term paper.

　 ----Great! You____read widely and put a lot of work into it.

A. must　　　　　 B. should　　　 C. must have　　 D. should have

19. You’ d better take something to read when you go to see the doctor___you have to wait.

A. even if　　　　 B. as if　　　　 C. in case　　　 .D in order that

18. He was educated at the local high school,___ he went on to Beijing University.

A. after which　　 B. after that　　　 C. in which　　 D. in that

17. Please remain___until the plane has come to a complete stop.

A. to seat　　　　 B. to be seated　 C. seating　　　 D. seated

16. You will be successful in the interview___you have confidence.

A. before　　　　 　 B. once　 　　　　　　　 　C. until　 　　　　　 D. though

15. He tried his best to solve the problem,____difficult it was.

A. however 　 　B. no matter 　　　　　　 　C. whatever　 　　 D. although