23. It won’t be long before such a thing _____ again.

　 A. happened　　 　　　 B. is happened　　 　　　　 C. will happen　　 　　　　 D. happens

22. The key to my door _____. I have looked for it everywhere, but I still _____ it.

A. is missing; can’t find　　 　　　　　　　　　　　　　 B. has lost; don’t find

C. has lost; haven’t found　 　　　　　　　　　　　　 D. has been gone; haven’t found

21. I don’t think Jim saw me, he _____ into space.

　 A. just stared　　 　　　 B. was just staring　　 　 C. has just stared　 　　 D. had just stared

20. Don’t interrupt me . I ___ letters all morning and have written five.

A. write　　 　　　　　　 B. have written　 　　　　 C. was writing　 　　　　 D. have been writing

19. So far solar energy ___ in the world.

A. has not been widely used　 　　　　　　　　　　　 B. is not widely used　

C. was not widely used　　　 　　　　　　　　　　　　　　 D. hasn’t used widely

18. It ___ every day so far this month.

A. is raining　 　　　　 B. rained　 　　　　　　　　 C. rains　　 　　　　　　　　 D. has rained

17. My pen ___ for two weeks. May I borrow yours, please?

A. has lost　　 　　　　　 B. had lost　 　　　　　　　 C. had been lost　 　　　　　　　 D. has been lost

16. You look worried. What ____ to you?

A. happens　 　　　　　 B. has happened　 　　　 C. happened　 　　　　　　 D. is happening

15. -Do you know our town at all?

-No. This is the first time I ___ here.

A. was　 　　　　　　　　 B. have been　　 　　　　　 C. come　　 　　　　　　　　 D. was coming

14. The pen I ___ I ___ is on my desk, right under my nose.

A. think; lost　 　　　　 B. thought; had lost　 　 C. think; had lost　 　　　　　　　 D. thought; have lost