21. ［2012九江模拟］—Excuse me, where can I get ________ application form?
—Go to ________ Window 10, please.
A. an; 不填 B. an; the
C. 不填; 不填 D. the; the
22. ［2012桐乡模拟］—Did you wait for him long?
—No, I hadn’t waited long ________ he appeared.
A. unless B. until
C. before D. since
