第二部分：英语知识运用(共两节。满分55分)
第一节：语法和词汇知识(共15小题；每小题1分，满分15分)
从A、B、C、D四个选项中，选出可以填入空白处的最佳选项。
21. If we expect much cleaner world, we should attract world's attention to protect it.
A. a; a B. a; the C. a; 不填 D. the; 不填
22. –-The terrible earthquake made 15 million people homeless.
---_________.
A. Certainly B. I agree with you C. It’s OK D. That’s the case
