题目内容：

怎样改英语简单句?
这里有几题,(最好说一下怎么改）
1.We didn't go out for a walk because it was raining.
We didn't go out for a walk_____ _____ the rain.
2.He was so excited that he couldn't go to sleep.
He was _____ ____ ____ go to bed.
3.I don't know when we will begin the work.
I don't know ____ ____ ____the work.
还有，复合句呢？怎么改？