31. I was just about to go to bed last night ______ the telephone rang.　

A. while　　 B. when　　 C. as　　 D. before

30. The world is ______ seven continents and four oceans.

A. made up of　 　B. make out of　 　C. made from　　 D. made in

29. ______ that I made a mistake, I made an apology ______ him.

A. Realized; to　 B. Realize; for　 C. Having realized; to　 D. Realizing; for

28. ______ on the top of the tower, and you can see the whole city.　

A. Standing　　 B. To stand　　 C. Stood　　 D. Stand

27. I think that his advice is well worth 　__　 .　

A. valuing　　 B. to be valued 　　C. of being valued　 　D. values

26. Only after we left the building ______ how dangerous the situation had been.

　 A. was I realized　　 B. I realized　　 C. did I realize　　 D. I was realized

25. ---You’ve missed such a good chance.　 ---Yes, I 　　　　that job the boss offered me.

A. must have taken　 　B. must take　　 C. should have taken　 　D. should take

24. In my opinion, you must try some of her home-made wine. It’s quite an unforgettable ___.

　　 A. experiment　　 B. experience　　 C. effort　　 D. skill

23. He is always full of ______ as if he never knew tiredness.

A. strength　 　 B. spirit　　 C. force　　　 　　 D. energy

22. One learns a language by making mistakes and ______ them.

　 A. correct　　 B. corrects　　 C. correcting　　 D. to correct