30. However, at times this balance in nature is disturbed, ____ a number of possibly unforeseen effects.

A. lying in　　 B. calling in C. taking in　 D. resulting in

29.--- He has to finish the experiment today. He must be in the lab,____?

---That s quite possible.

A. mustn't he　 B. won't he　 C. doesn't he　 D. isn't he

28. Let us suppose that you are in____ position of____ parent. Would you allow your child to do such a thing?

A. a; a　　 B. a; the　 C. the; a　 D. the; the

27. Our TV sets sell well, but ten years ago no one could have imagined such a big share in the market that they ____.

A. were having　 B. had had　 C. were to have　 D. had

26. In salad bars the waiter does not bring you salad. You have to____ yourself, usually to as much as you want.

A. bring　 B. serve　 C. help D. supply

25. ---How do you like the film?

　---There was nothing special--- it was only ____.

A. average　　 B. usual　　 C. normal　 D. common

24.--- What are you going to do next?

--- To write a science story about outer space ___ by Science and Technology Press.

A. published　　 B. being published

C. to be published　　 D. publishing

23. I'll be home late, but please don't stay ____ for me.

A. up　　 B. in　　 C. over　　　 D. on

22. ---Mary has a very low opinion of George.

---It can' t be any worse than ____ of her.

A. he　 B. his　　 C. him　　 D. he does

21.--- ____ at the new school?

--- Fine, I've got used to the life there and I've made some friends.

A. How are you　 B. How are you doing

C. Are you getting on well　 D. How do you do