By the time he realizes he a mistake, it’ll be too late for him to change his mind.
A. makes
B. made
C. has made
D. had made
网友回答
A. makes
B. made
(答案→)C. has made
D. had made
解析：考察时态。By与完成时连用，且by the time引导是时间状语从句，，使用一般现在时表示将来时，主句使用将来时。根据句意可知是他认识到自己已经犯了错误。