问题
选择题
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
答案
答案：C
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。