21. The lawyer questioned the witness about  ______.

A. what knew he                                         B. what did he know

C. he knew                                                 D. what he knew

22. By 2003 my hometown had become  ______ industrial city in the province.

A. one of the three largest                            B. a third largest

C. the third largest                                       D. the three largest

23. The concept  ______ to describe the way nations behave，but it is equally applicable to individuals.

A. is most often used                                   B. most often use

C. is often most used                                    D. is most used often

24. Japanese scientists do not know for sure  ______ Mount Fuji will erupt again.

A. where                                                    B. that

C. when                                                      D. which

25. It’s not good laughing  ______ other people’s shortcomings.

A. with                                                       B. on

C. about                                                     D. at

26. An object is said  ______ if its temperature is much higher than that of our bodies.

A. to be hot                                                B. as being hot

C. hot                                                         D. as hot

27. After that quarrel，Sam didn’t talk to Paul  ______.

A. any more                                                B. no more

C. much longer                                           D. no longer

28. It allows advertisers to combine sight，sound and motion，thus  ______ to almost all the viewers’senses.

A. appeal                                                    B. and appeals

C. appealing                                                D. appeals

29. If it  ______ tomorrow，we’ll have to stay indoors.

A. would rain                                              B. will rain

C. rained                                                    D. rains

30. He  ______ the Chinese Volunteers Army in 1951.

A. joined                                                    B. had joined

C. has joined                                               D. has been joined