21. The boy came to ____ life after the operation, although he was once ____ failure.
A. a; a B. / ; a C. a; / D. /; /
22. ---I wonder if I _____ smoke here.
---No, you ______ . Couldn’t you see the sign “NO SMOKING” on the wall?
A. can; needn’t B. may; mustn’t C. must; can’t D. shall; won’t
23. You must ______ the bowls and dishes properly before they are put away.
A. wipe up B. wipe over C. wipe off D. wipe out
24. My sister is on a special _______ to lose _______ weight.
A. food; / B. food; her C. diet; / D. diet; her