第二部分：单项填空（共15小题；每小题1分，满分15分）
21. _______ person like him won’t be satisfied with _______ little progress that he has made.
A. The; a B. The; / C. A; / D. A; the
22. I’m writing ______ your letter of September 6.
A. in response of B. in response to C. in response for D. in response about
23. The man at the meeting advocated ______ a more long-term view.
A. to take B. taking C. take D. having taken
