二.单项选择（共15小题，每小题1分，计15分）
从A.B.C.D四个选项中选出一个可以填入句中空白处的最佳答案。
21. —How did you know that our Chinese teacher is in a bad _____ today?
—Don't you know that many students in our class failed in the Chinese exam.
A. decision B. behaviour C. mood D. thought
22. “I don't know ____ to do it next. Could you please give me a hand?” the boy said to his best friend.
A. what B. how C. who D. which
