21. It doesn’t make _____ difference whether he is in _____ favour of or against the plan.
A. a; a B. a; 不填 C. 不填; a D. 不填; 不填
22. When you are home, give a call to let me know you _____ safely.
A. are arriving B. have arrived C. had arrived D. will arrive
23. —I saw John in the library yesterday.
—You _____ him; he is still in Japan.
A. mustn’t have seen B. needn’t see C. mightn’t see D. can’t have seen
