21. Sarah looked at _____ finished painting with ___ satisfaction.
A. / ; a B. a; the C. the; / D. the; a
22. We _____ have bought so much food now that Suzie won’t be with us for dinner.
A. may not B. needn’t C. can’t D. mustn’t
23. It suddenly occurred to him ___ he had left his keys in the office.
A. whether B. where C. which D. that
