从A、B、C、D四个选项中，选出可以填入空白处的最佳选项。
21. —Would you like to come on Friday or Saturday?
—______
A. Yes, of course. B. Another is better. C. What’s the matter? D. Either is OK.
22. Will you have a free evening tonight? ______, let’s have a dinner together.
A. If not B. Why not C. If so D. What’ more
23. I bought a dress for only 10 dollars in a sale; it was a real ______.
A. exchange B. business C. bargain D. trade
