初中英语大大

宾语从句。。。
可以
I don"t know( that) how to do it.

请注意：I don"t know how to do it.这里疑问副词+不定式根本不是个宾语从句！！！
I don"t know how I can do it. 这个才是宾语从句。

I don"t know that how to do it. 这是个错误的句子，不能加that！！

定语从句里不可以这样用。

老弟啊，I don"t know how to do it.里面的how to do it只是一个含有疑问副词的不定式短语，根本不是句子，何谈宾语从句。I don"t know how I can do it.这个才是宾语从句。

可以...

定语从句不可以

Where is she?
Where is the closet Chinese embassy?
Where are you going?
Where do you think you are going?

Whose hat and book is that?
Whose stuff is this?

Who the hell do you think you are?
Who are you?
Who is that?

What are you doing!!!
What is that thing that you are holding?
What can you tell me?

I don't know how to do it.这是疑问词+不定式结构,而不是宾语从句.只能说它们之间可以改写(当主句和从句的主语一致时).
=I don't know how I can do it. 这是宾语从句。
定语从句里不可以这样用。
我是初中英语老师,这一解释绝对正确，希望