一、名词性从句的概念及种类
在句子中起名词作用的句子叫名词性从句（Noun Clauses）。名词性从句的功能相当于名词词组，它在复合句中能担任主语、宾语、表语、同位语、介词宾语等，因此根据它在句中不同的语法功能。名词性从句又可分别称为主语从句、宾语从句、表语从句和同位语从句。
这几类从句用法复杂、学习难度较大，考生在考试中丢分现象严重。
下面向大家介绍名词性从句的用法、特点、考点等，以帮忙职称英语考生来重新熟悉并达到熟练运用，达到提高成绩的目的。
二、考点聚焦
1、名词性从句中连接词的运用
名词性从句中的连接词有连词that / whether / as if，连接代词what / who/ which / whose / whatever / whoever / whomever / whichever，连接副词where / when / why / how / wherever / whenever。
（1）that的用法。
①主语从句、表语从句、同位语从句中用that但不能省略。如：
That they are good at English is known to us all.
The problem is that we don’t have enough money.
She expressed the hope that they would come to China one day.
②宾语从句中的连接词that有时可省有时又不可省，在以下几种情况中that不能省略：
（A）当that从句和主句谓语动词之间有插入词语或者从句主语之间有插入语时，that不可省略；
（B）当that 从句与另一名词性从句并列作宾语时，that不能省；
（C）当that作介词宾语时，that不可省掉。如：
Everyone knew what happened and that she was worried.
The reason lies in that she works harder than the others do.
③ that从句作主语和宾语时，可以用it 来替换成以下几种结构表达。
(A)It is clear/certain/likely/true/surprising that…
（B）It is a pity/shame/good idea/no wonder that ...
（C）It is said/reported/ believed/known/thought/suggested that …
（D）It seems/happens that。如：
It happened that I went out last night.
It is said that China will win in the World Cup.
④that和what的区别。
that 引导名词性从句时，在主从句中不以当任何句子成分，也没有任何含义；而what引导名词性从句时，在主从句中都要充当一定的句子成分，what可以分解成定语从句中的先行词 + 关系代词即常说的先行词 + that。如：
It’s shame that he has made such a mistake. Do what he says.
⑤同位语从句与定语从句中that的区别。
同位语从句中的连词that只起连接作用，在从句中不担当任何句子成分；而定语从句中的关系代词that在句中做宾语或主语，宾语与先行词有修饰关系。如果句子是同位语从句，就应用连词that而不能用which.同位语从句一般放在表具体含义的名词后解释名词的含义或内容，如以下名词：news、fact、suggestion、truth、plan、belief、doubt、possibility、idea等，而定语从句只是对先行词的限定和修饰。如：
They expressed the hope that they would come to visit China again.(同位语从句)
The hope she expressed is that they would come to visit China again.（定语从句）
（2）whether和if的用法。
①whether和if在宾语从句中可以互换，但是作介词宾语时连接词一般用whether。如：
It all depends on whether they will come back.
②后面直接跟or not 时用whether。如：
I didn’t know whether or not he had arrived in Wuhan.
③主语从句表语从句中只能用whether。如：
Whether the meeting will be put off has not been decided yet.
The question is whether they have so much money.
④whether可以引导同位语从句，用以说明前面的名词的内容，if不能。如：
We ought to discuss carefully the question whether we can do it or not.
⑤whether常与or连用表示一种选择，if不能这样用；whether也可与动词不定式连用但if不能。如：The question of whether they are male or female is not important.
I have not decided whether to go or not.
⑥间接引语位于句首时或者是间接引语提前时用whether不用if。如：
Thank you, but whether I’ll be free I’m not sure at the moment.
⑦whether可引导一个让步状语从句表示“不管”、“无论”，而if不能。如：
Whether he comes or not, we will begin our party on time.
（3）疑问词 + ever和no matter + 疑问词的区别。
①疑问词 + ever可引导名词性从句，在主从句中要充当一定的部分。如：
Whoever breaks the rule must be punished.
You can choose whatever you like in the shop.
②疑问词 + ever还可引导让步状语从句。如：
Whoever breaks the rule, he must be punished.
Whatever you do, you must do it well.
③no matter + 疑问词只能引导让步状语从句。如：
No matter what you do, you must do it well.
No matter who breaks the rule, he must be punished.
（4）when和where引导的同位语从句与定语从句的区别。
when 和where前面的名词若是表示时间、地点的名词，则when和where引导的是定语从句，否则则为同位语从句。如：
They put forward the question where they could get the money.
This is the place where the accident happened.