when引导的主句从句的时态

　　I didn't use to like him much when we were at school.

　　以前我们同学时，我并不太喜欢他。

　　When I left they were all still hard at it.

　　我离开的时候他们都还在努力工作。

　　When is the best time to ring New York?

　　什么时间给纽约打电话最好？

　　It was a difficult situation, when you think about it.

　　仔细想来，当时处境是很困难的。

　　When they set out they were well prepared.

　　他们出发时有很充分的准备。