i don't know what is he doing?

问题描述:

i don't know what is he doing?
i don't know where does he live?和i don't know what is he doing?哪句话正确?错误的那句原因是什么?
还有一个问题 ask him how much did it cost ask him how much it costs?这两句话那句是正确的?错误的原因是什么?

这两句都不正确,它们都是宾语从句.从句部分要保持陈述语序即主谓宾
I don't know where he lives .
I don't know what he is doing