17. The thought ______ he might fail in the final exam worried him.

　A. which　B. that　C. when　D. /

16. That is ______ there appears a rainbow in the sky.

　A. what　B. when　C. why　D. however

15. The trouble is ______ we are short of tools.

　A. what　B. that　C. how　D. which

14. It doesn't matter _____ I rest or not.

　A. if　B. whether　C. that　D. when

13. She wanted to know ______.

　A. whether I knew her and where did she work.

　B. if I knew her and the factory she worked there.

　C. whether I knew her and the factory she worked.

　D. if I know her and the factory where she worked.

12. Computers can only give out _____ has been stored in them.

　A. that　B. which　C. what　D. anything

11. Nobody knew _______.

　A. where he comes　　B. where he was from

　C. where he is from　D. where does he come from

10. ______ we will go to the beach tomorrow depends on the weather.

　A. Why　B. If　C. Where　D. Whether

9. ______, paper was first made in China.

　A. It is known to all　B. We all know

　C. It is known that　　D. As it known to all

8. In the daytime the stars are not seen to twinkle ______.

　A. in a space　B. in the space　C. in space　D. on space