第二部分：英语知识运用（共两节．满分35分）
第一节：单项填空（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。
21. —I’m sorry, but there’s no smoking in this section on the train.
—Oh, I ______ that, and I won’t again.
A. don’t know B. didn’tknow C. won’t know D. haven’t known
22. Three fourths of the homework _______ today.
A. has finished B. has been finished C. have finished D. have been finished
