第二部分：英语知识运用（共两节；满分35分）
第一节：单项选择 (共15小题；每小题1分, 满分15分)
请认真阅读下面各题, 从题中所给的A、B、C、D四个选项中, 选出最佳选项, 并在答题纸上将该项涂黑。
21. —Congratulations! I have heard that you will be a volunteer for ________2010 Shanghai Expo.
—Thank you, and I firmly believe it will be ________ great success.
A.不填; the B. the; a C. the; the D.不填; a
22. —Did you find the missing couple in the mountain yesterday?
—No, but we ________ to get in touch with them ever since.
A. have been trying B. have tried C. are trying D. were trying
