1. B. mustn't be sleeping

2. A. in

3. B. in

4. A. any other countries

5. A. to be chosen

6. A. must be sleeping

7. C. changed

8. D. have passed

9. C. while driving

10. D. for

11. A. him not to smoke

12. A. so that he decided

13. A. dropping

14. C. than buy

15. B. most anyone

16. C. the electicity went out

17. C. to

18. C. no being responsible

19. D. to see anything

20. A. so sweetly did she sing

21. C. to

22. A. from

23. C. Being a famous naturalist

24. A. don't need to rebuild

25. B. when

26. A. are appearing to take

27. C. choosing

28. B. so I think she mustn't have locked it

29. C. must have been mistaken

30. C. when he was writing a letter

31. C. Being a very famous singer

32. A. too

33. D. to be written

34. A. to talk

35. B was alive

36. C. an interested boy in music

37. B. I saw an accident

38. A. intelligent

39. B. So strong is he

40. C. He is intelligent