When Tom was sleeping,a thief broke into his house

1.这句话错了,应该这样说：
Tom was sleeping when a thief broke into his house
2.when引导的是时间状语从句,如果一个复合句中句子没有逗号,前面主句后面从句,如果一个复合句有逗号,前面从句后面主句.另引导词when,where等引导的都是从句
3.换成while应该这样说：
While Tom was sleeping,a thief broke into his house
while引导的从句多数用进行时态,经常用于一边做...一边做...
when引导的从句多数不用进行时,表示when引导的动作突然插入