I don't know ( ).A.what to do it B.how to do it C.what to do D.to do what

问题描述:

I don't know ( ).A.what to do it B.how to do it C.what to do D.to do what

B 或 C
know 是个动词,后面接名词或从句
如果接what,名词,后面的to do 是作为修饰what 的不定式,表示做什么,像what to eat(吃什么),what to buy(买什么);
what to do 的do 修饰了what 以后,已经有do 的对象了,所以不必再加it,改成what to do with it (怎么处理它)可以.
如果接how ,表示一种方式,怎么做,可以直接说how to do it 这里的to do不表示修饰,而是目的,怎么去做