第二部分：英语知识运用（共两节，满分35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,并在答题卡上将该项涂黑。
例: It is generally considered unwise to give a child he or she wants.
A. however B. whatever C. whichever D. whenever 答案是B。
21. If we expect much cleaner world, we should attract world's attention to protect it.
A. a; a B. a; 不填 C. a; the D. the; 不填
