第二部分 英语知识运用（共两节，满分45分）
第一节：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，选出可以填入空白处的最佳选项。
21. Studying in China was quite_____ experience to Mary, _____ that she would never forget.
A. an, one B. an, it C. /, it D. an, /
22. It was there, the police believe, _________ she was able to activate the recorder she kept in her bag.
A. until B. which C. that D. when
