题目内容：

关于before和after的用法
1.The roof fell __he had time to dash into the room to save his baby.
2.Time passed quickly and three weeks went by _we knew it.
答案都是before,我怎么觉得用after 也一样符合逻辑啊

优质解答

肯定是before啊
1、在他冲进房间救他孩子之前,屋顶掉了下来
他还来不及救～
主要是题中用了 have time to do sth.有时间做某事,所以只能有before
如果原句改成The roof fell after he had dashed into the room to save his baby 意思就是他救出他的孩子后屋顶掉下来了
2.时间过得好快啊,我们意识到之前,三个星期就过去了
也就是说三个星期不知不觉就过去了～
如果用after,他们意识到过了三个星期的话,前面就不会感慨时间过得快了～