by the time的用法及例句

by the time的用法

1、到…时候为止

表示到...为止,一般要求主句用过去完成时.

例句：

He had left by the time we reached home.

当我们到家的时候他已经走了.

The movie had begun by the time we got there.

当我们到那儿的时候,电影已经开始了.

2、到……的时候

(1)可以表示将来的时间. 主句用将来完成时,而从句用一般现在时来表示将来的动作.

I will have finished the work by the time my father comes back.

(2)可以表示过去的时间. 主句用过去完成时,而从句用一般过去时.

He had built a lab for himself by the time he was 12 years old.

注：如果只是说过去某个时候的状况，用过去时，而不用完成时。

例句： By the time the war was over , death and suffering were to be seen everywhere.

在战争结束的时候，到处可见死亡和饥饿。

这里没有“死亡和饥饿”已经完成的意思，只是描述当时这个时间点的状况。所以用过去时。