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. I was born in China and have been living here. I can’t imagine ______ anywhere but China.
A. work B. working C. to work D. having worked
22. --Did you hear something?
--No. I ______ but I ______ anything at all.
A. listened; have heard B. have listened; hear
C. am listening; hadn’t heard D. was listening; couldn’t hear
