英语中的名词性从句的分类及详细介绍

引导名词性从句的连接词可分为三类：
连接词：that,whether,if 不充当从句的任何成分）
连接代词：what, whatever, who, whoever, whom(ever), whose(ever), which(ever).
连接副词：when, where, how, why ,how many,how much,等,代词在从句中可以作主语,宾语,表语,定语,而副词在从句中作状语
eg.What you said sounds reasonable.
Whatever you said is right.(这两句中都是主语从句)
eg:He wants to know whether/if we can help him.(动词后宾语从句用这两个是否都可以)
They are talking about whether we will go for a picnic.(介词后宾语从句,只用这一个是否)
eg:What I can't understand is why he left without saying a word.(why引导的是表语从句)
eg: I have no idea why he left without saying a word .(why引导的同位语从句,即对前一个名词的解释或说明)