名词性从句：主语从句，宾语从句，表语从句，同位语从句

名词性从句相当于名词，可分别作主句的主语、表语、宾语和同位语。因此，名词性从句分为主语从句、表语从句、宾语从句和同位语从句。

 1. What it was to become was a mystery.

 2. I don't know who will help Henry t o win the bet.

 3. His trouble is that he doesn't know anybody in London.

连接词:that,whether,if,as if ,as though

连接代词 ：what, who, whom, which, whose,

whatever, whoever, whomever, whichever

连接副词：when,where,how,why

宾语从句在复合句中起宾语作用，可以作动词的宾语，也可以作介词的宾语。引导宾语从句词有连词that，if，whether；连接代词who，whose，what，which；连接副词when，where，how， why等。

e.g. (1) I think (that) women can reach very high achievements in many fields of scienc e.

2) I wonder whether/if she remembered how many babies she had delivered.

3) Do you know who/wh om Jack was speaking to?

注意点：1).宾语从句一律用陈述句的语序.