英语语法,before when\after when做A事,before when做B事 在这句话里,A事先发生还是B事先发生?

英语语法,before when\after when做A事,before when做B事 在这句话里,A事先发生还是B事先发生?
英语语法,before when\after when
做A事,before when做B事
在这句话里,A事先发生还是B事先发生?

英语语法,before when\after when做A事,before when做B事 在这句话里,A事先发生还是B事先发生?
用beforeA事先发生 .如 We waited for a long time before he came.我们等了很久他才来.
He rushed out before I could say a word.还没等我说话他就冲了出去.
I had finished my homework before my mother came back.在妈妈回来之前我就完成了作业.
用when时要看句型.be about to do ,when,正在做某事这时另一件事发生了.如
I was about to leave when he came.我正要走这时他来了.
had done sth when ,刚做完某事这时另一件事发生了.如
I had finished homework when the power was off.我刚刚完成作业电就停了.
be +doing sth when .正在做,这时另一件事发生了
I was driving along the road when an accident happened.我正在路上开着车这时发生了交通事故.
,when,表示前面的事发生在后面的事之中.如
The teacher came in when we were talking and laughing happily.我们正高兴地说着笑着的时候老师走了进来.