21、―Mum, you always tell me that if I work hard, I will pass the exam.

―But you must admit that you ____, so far.

A. didn’t          B. hadn’t              C. haven’t           D. don’t

20、There is a new problem involved in the popularity of private cars ____ road conditions need to be improved.

A. that          B. which              C. where            D. when

19、The Opening Ceremony of the 29^th Olympic Games is a great success, ____ that has surprised the world.

A. it                            B. one                C. the one             D. which

18、Thank you for all your hard work last week. I don’t think we ____ it without you.   

A. can manage     B. could have managed  C. could manage       D. can have managed

17、After walking for ten minutes, she suddenly realized that she ____ in the wrong direction.

A. was walking   B. has been walking      C. had been walking     D. walked

16、____ she is not so healthy ____ she used to be?

A. How is it that; as       B. Why is it that; what   C. Is it why; that 　      D. How it is that; as

15、____ sales down by 30%, the company has to lay off many clerks.        　

A. For 　           B.  As 　　           C. Through 　          D. With

14、 At length, we found ourselves in a pleasant park with trees providing shade and ____ down to eat our picnic lunch.

A. sitting        B. sat                 C. to sit                 D. having sat

13、We hope that the measures to control the stock market, ____ are taken by the government, will work.

A. that                 B. where              C. which               D. what

12、―Mr. Smith, I can’t go on with my reading.

―I’ve already told you the last three parts of the article ____ the most difficult to understand.

A. is                   B. are                C. had been             D. were