by the time 的用法是什么

by the time 有两个意思1。到。。。为止,一般要求主句用过去完成时。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)…当……的时候;如果只是说过去某个时候的状况,用过去时,而不用完成时。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。By the time we arrived the meeting was over。我们到达时,会议已结束了。