when后接过去进行时从句句子主句用什么时态?

问题描述:

when后接过去进行时从句句子主句用什么时态?

比较常见的是:
1.一般过去时(表示在进行过程当中出现的结果)
He hurt his leg when he was playing football.
2.过去进行时(表示两方面同时做的事情)
He was doing his homework when I was cooking.