问题补充:
I am sorry I can’t meet you at the station. I by the time you come back from abroad.
A. am leaving
B. had left
C. will have left
D. have left
答案:
A. am leaving
B. had left
(答案→)C. will have left
D. have left
解析:考查时态。by+过去的时间,主句使用过去完成时;by+将来的时间,主句用将来完成时。by the time you come back from abroad所知的时间是将来,故主句用将来完成时,即will have done sth。故选C。