15. I will work as hard as I can _____ for the final exam.

A. prepare　　　　　　 B. to prepare　　　　 C. preparing　　　 D. prepared

14. _____ there are many different interpretations of our body language, some gestures seem to be universal.

A. When　　　　 　　　B. While　　　　　　 C. Because　　　　 D. Since

13. The speaker raised his voice but still couldn’t make himself _____.

A. hear　　　　　　　 B. to hear　　　　　　 C. heard　　　　　 D. to be heard

12. Theme parks try to make sure that visitors leave _____ more about their theme.

A. to know　　　　　 B. knowing　　　　　 C. know　　　　　　 D. known