I am sorry that I can not meet you at the airport. I Changsha by the time you e back from abroad.
A. am leaving
B. will leave
C. will have left
D. have left
网友回答
A. am leaving
B. will leave
(答案→)C. will have left
D. have left
解析：考查时态。根据时间状语by the time you e back from abroad在他从国外回来之前，可知用将来完成时，故选C。