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）
21. If a computer crashes，you will lose the file you _____ on if you don’t save it early enough.
A. are working B. work C. will work D. worked
22. If the martial class I signed earlier changes to Sundays, I will have to ________ so that I can ________ my son from his violin lessons.
A. drop in, pick out B. drop off, pick up
C. drop out, pick up D. drop by, pick out
