21. Our boss is still on _____ vacation, so the secretary will be in _____ charge of the meeting today.
A. a; / B. the; the C. /; / D. the; a
22. — Mr. Zhu, would you mind if I asked you a few questions about the coming school culture and art festival?
— __________ Go ahead.
A. Yes, please. B. Not at all.
C. No, please don’t. D. Yes, I don’t.
