30. (’06辽宁，29) I think it is necessary for my 19-year-old son to have his own mobile, for I sometimes want to make sure if he _____ home for dinner.

A. come　 　　　　　　　　　 　B. comes　　 　　 　C. has come　 　D. will come

29. (’06辽宁，27) The father as well as his three children ________ skating on the frozen river every Sunday afternoon in winter.

A. is going　 　　　　　　　　 　B. go　 　 　C. goes　　 　　　 　D. are going

28. (’06山东，28) Although the causes of cancer_______, we do not yet have any practical way to prevent it.

A. are being uncovered　 　　　 B. have been uncovering　　 C. are uncovering　 　　　　　　　 D. have uncovered

27. (06陕西，12) The construction of the two new railway lines ______by now.

A. has completed　　 　 B. have completed　　 C. have been completed　　 　　　 D. has been completed

26. (’06陕西，7)---- You look very tired. _____ at all last might?

----No, not really. I’m tired out now.

A. Do you sleep　　　 B. Were you sleeping　　　 C. Did you sleep　　　 D. Had you slept

25. (’06江苏，23) ----I don’t suppose the police know who did it.

---- Well, surprisingly they do. A man has been arrested and _______now.

A. has been questioned　　　　　 B. is being questioned　　　　　　 C. is questioning　　 D. has questioned

24. (’06安徽，25)　 I ______ along the street looking for a place to park when the accident_________.

A. went; was occurring　　 B. went; occurred　　　 C. was going; occurred　　　　 D. was going; had occurred

23. (’06浙江，16) My friend, who _____ on the International Olympic Committee all his life, is retiring next month.

A. served　　 B. is serving　　 C. had served　　 D. has served

22. (’06浙江，7) The company had about 20 notebook computers but only one-third ______ used regularly. Now we have 60 working all day long. 　

A. is　　 　　 B. are　　 　C. was　 　　　　 　D. were

21.(’06浙江，6)This machine ______. It hasn’t worked for years.

A. didn’t work　 　　　　　　　　　 B. wasn’t working　 　　 　C. doesn’t work　 　　　　　　 D. isn’t working