第二部分： 英语知识运用 （共两节， 满分35分）
第一节：单项填空 （共15小题；每小题1分，满分15分）
21. Jumping out of ____ airplane at ten thousand feet is quite ____ exciting experience.
A. /; the B. /; an C. an; an D. the; the
22. _____ that air conditioners cause so much pollution, I would never have bought one.
A. Had I known B. I had known C. Were I to know D. Did I know
