请认真阅读下面各题，从题中所给的A、B、C、D四个选项中，选出最佳选项，并在答题卡上将该项涂黑。
21. Last month, thousands of workers in that city went on _____ strike, demanding lower taxes and ______ end to cutting staff members.
A. a; the B. a; an C. 不填; an D. 不填; the
22.—He is eager to try something he has never tried before.
—Oh, I see. That’s _______ he’s different from others.
A. when B. where C. how D. what
