( ) 21. Michael ______ be a policeman, for he’s much too short.

　　A. needn’t B. can’t C. should D. may

　　( ) 22. ______ I know your name?

　　A. May B. Will C. Shall D. Must

　　( ) 23. You ______ be more careful next time.

　　A. have to B. may C. must D. might

　　( ) 24. You ______ miss the lesson, though we ______ have it on Thursday.

　　A. mustn’t; needn’t  B. needn’t; mustn’t  C. mustn’t; mustn’t  D. needn’t; needn’t

　　( ) 25. This pen looks like mine, yet it isn’t. whose ______ it be?

　　A. must B. may C. would D. can

　　( ) 26. What kinds of homes will we live in the future? Nobody ______ be sure, but scientists are working out new ideas now.

　　A. will B. may C. can D. must

　　( ) 27. I ______ like to know where you were born.

　　A. shall B. should C. do D. may

　　( ) 28. ______ you be happy!

　　A. Might B. Must C. Wish D. May

　　( ) 29. A teacher ______ do every exercise, but a student must.

　　A. may not B. needn’t C. can’t D. mustn’t

　　( ) 30. The matter ______ be changed into a gas, but it _______ be heated to its boiling point.

　　A. may; needn’t B. may; can C. mustn’t; needn’t D. can; must