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（）21. In those days we seldom went to the theatre， but we saw films

A. now and then

B. after a time

C. once and again

D. in a while

（）22. Many thingsimpossible in the past are quite common today.

A. having been considered

B. to be considered

C. considering

D. considered

（）23. I'm not naturally a morning person，I have three clocks set for about 6：30 a.m.

A. because

B.so

C. though

D. all

（）24. that the family had taken with them was one bottle of orang

A. Anything

B. Everything

C. What

D. All

（）25. The newspapers and magazines in the reading-roomoutsid

A. are not to be taken

B. are not to take

C. are not to be taken to

D. are not taken to

（）26. A pipeline will be built tosome eastern provinces with natural gas from the west of China.

A. supply

B. send

C. sell

D. offer

（）27.Is it really necessary to spend an hour in the bathroom every morning your hair？

A. to comb

B. comb

C. combing

D. combs

（）28.he first heard of the chemist.

A. That was from the teacher that

B. It was the teacher whom

C. It was from the teacher that

D. That was the teacher whom

（）29. Passengers are advised nottheir bags unattende

A. having left

B. to leave

C. leave

D. leaving

（）30.has been pointed out before， air pollution is becoming more and more serious in large cities.

A.That

B. What

C. Which

D. As