第二部分．单项选择（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. — What a mess! You need to clean the classroom after school!
— But the final exam is approaching!
A. constantly B. mildly C. thoroughly D. previously
22. —So hard _______ in the past few months that he has made great progress in English.
—I can see that；only a few mistakes _______ in the exam.
A. has he worked; did he make B. he has worked; did he made
C. he has worked; he made D. has he worked; he made
