21. --– Have you seen ________ pen? I left it here this morning.
---- Is it ____________ black one? I think I saw it somewhere.
A. a; the B. the; the C. the; a D. a; a
22. There are a lot of new buildings on ______ side of the street.
A. either B. every C. both D. all
23. We’ll try to do the work with ________ money and _______ people.
A. few; little B. little; few C. less; fewer D. fewer; less
24. ---- Can you stay here for lunch?
---- Sorry, I ________. I have something important to do.
A. don’t B. didn’t C. needn’t D. can’t