13.The reason why he was late was ____ he had taken a wrong bus.

　 A. because　　　　 B. whether　　　　　　 C. because if　　　　　 D. that

12.The truth is ___ he doesn't work hard enough.

　 A. why　 　　　　 B. what　 　　　 C. that　 　　　　　　　 D. which

11.The reason for his success is _______ he worked hard.

　 A. why　　　　　　 B. that　　　　　　 C. because　　　　　　 D. for

10.What I asked him is ____ the story happened.　　　　 　

A. when and what　　　　　　　　　　 B. what and where　

C. which and where 　　　　　　　　 D. when and where

9. The problem is not ___ we leave, but ____ we can get there.

　 A. when; how B. when; where　 C. how; which　　　 D. where; when

8. It looks ______ it's going to rain.　

A. that　　　　 B. as　　　 C. as if　　　　　 D. that

7. This is ______ .　

A. how did they get to the city　 B. what did they get to the city

　 C. how they got to the city 　 D. what they got to the city

6. The news ____ Lincoln was murdered filled the American people's hearts with deep sorrow.

A. which　　　　　　 B. when　　　　 C. that　　　　　　　　　 D. how

5. We were all very worried over the fact _____ you were ill.

　 A. that B. what　　　　　 C. which　　　　　　　 D. about which

4. Do you doubt ________ I believe you ?

　 A. that　　　　 B. which　　　　 C. whether　　　　　　 D. if