I don’t know what to do.I don’t know how to do.( × ) 第二句 how 怎么错了?

问题描述:

I don’t know what to do.I don’t know how to do.( × ) 第二句 how 怎么错了?
I don’t know what to do.(正确) I don’t know how to do.( × )

第二句应该是:
I don't know how to do it .
how 是副词,不能作 to do 的宾语,所以必须加 it 作宾语.
I don't know what to do .中 what 是 代词,可以作宾语.