15. Mary speaks in a low voice； ____ is difficult to know what she is saying.

　　 A. it　　 B. that　　 C. so　　 D. she

14. Was it because he was ill ____ he asked for leave？

　　 A. and　　 B. that　　 C. that's　　 D. so

13. It was on October 1st ____ new China was founded.

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

12. It was in the rice fields ____ we had our league meeting.

　　 A. where　　 B. that　　 C. in which　　 D. on which

11. It was through Xiao Li ____ I got to know Xiao Wang.

　　 A. who　　 B. whom　　 C. how　　 D. that

10. How long ____ to finish the work？

　　 A. you'll take　　 B. you'll take it　　 C. will it take you　　 D. will take you

9. ____ four years since I joined the Army.

　　 A. There was　　 B. There is　　 C. It was　　 D. It is

8. The climate of Shanghai is better than ____ of Nanjing.

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

7. We think ____ our duty to pay taxes to our government.

　　 A. that　　 B. this　　 C. its　　 D. it

6. ____ will do you good to do some exercise every morning.

　　 A. It　　　 B. There　　　 C. Those　　 D. You