what和how引导的从句
问题描述:
what和how引导的从句
They want to know _________do to help us.
答案是填what.
那么为什么不能用how呢?在此句子中,what充当从句的什么成分?
答
They want to know what to do to help us.
know+疑问词+不定式 等于相应的宾语从句:They want to know what they can do to help us.
因为do缺宾语,所以用what 作宾语,而how是作状语的,固不可选.
如果变化一下就只能选how了:
They want to know how to do it to help us.