by the time he realizes the mistake he has made,it will be too late for him to do anything about i

问题描述:

by the time he realizes the mistake he has made,it will be too late for him to do anything about i
为什么用has made?

整句是主将从现,从句by the time he realizes 是现在时,从句的从句the mistake he has made用现在完成时,表示在realizes的时候the mistake已经发生完毕