16. Our country has done something to stop population i                .

17. I love collecting stamps because I can learn much k                 from it.

18. Please r                 what you said just now. I didn't hear clearly.

19. Scientists have d                 a new virus. It is very important to medical research.

20. Please read a                 so that everybody can hear you.

21. The young singers all had clear English p                .

22. The e                 you use might depend on whom you are speaking to.

23. We all know blue c                 the feeling of harmony.

24. He was awarded because he took an a                 part in class activities.

25. Don't drive too fast. Please drive at a safe s                .

26. Our country's economy(经济) is i                 rapidly.

27. Books give us k                 and make us happy.

28. Please listen to the tape and r                 what you've heard.

29. The scientists haven't d                 any life on Mars yet.

30. Speak a                , please. I can't hear what you said.

31. Doctors tell us that eating burnt food can                 (增加) the risk of cancer.

32. The educational CD-ROM can help us learn a lot of                 (知识) about science.

33. Would you mind                 (重说) your suggestions? I didn't hear it clearly.

34. --- When did Columbus                 (发现) America?

--- In 1492.

35. Can you tell me the                 (发音) of this word?

36. Wang Kai likes                 (物理学) best.

37. Mother tells the children not to shout too a                (大声的) in the hospital.

38. Linda is such a              &nb