he will have arrived by this time tomorrow.为什么要用现在完成时?

问题描述:

he will have arrived by this time tomorrow.为什么要用现在完成时?
明天的这个时候他已经到了.
将来完成时如果应用于时间状语从句中,就要用现在完成时来代替.

我举个例子:I will go to school when he has arrived by this time tomorrow.当他明天这个时候到的时候,我就会去上学去了.如果你不变成现在完成时,一看就不对:I will go to school when he will have arrived by ...