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。
21. —John, it is your turn to clean the floor this afternoon.
—_____ I was right on duty yesterday.
A. Pardon? B. Why not? C. I can' t agree more. D. Are you kidding?
22. I don't want to bring up the topic,___ why on earth did you get home that late last night?
A. but B. and C. or D. so
23. Mr. Smith has two sons, one of _____ working as a bus driver now.
A. who B. whom C. them D. whose
