二、单项填空（共15小题，每小题1分，满分15分）
从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. —How about _______ controlled breeding program the US government began to save the red wolf?
—I should say it was _______ success; you see its number has increased.
A. a; a B. the; a C. a; 不填 D. the; 不填
22. —Linda didn’t invite us to her birthday party.
—_______? I don’t care.
A. For what B. So what C. What’s on D. What’s up
23. To her joy, Della earned first the trust of her students and then _______ of her colleagues.
A. one B. ones C. those D. that
