名词性从句在复合句中具有名词的性质的作主语、表语、同位语、宾语的从句叫名词性从句。
因此，我们把主语从句、表语从句、同位语从句和宾语从句这四种从句统称为名词性从句。
主语从句(subject clauses)在复合句中起主语作用的从句叫主语从句。
引导主语从句的词有从属连词、、关系代词、连接副词等。
引导主语从句的关联词有从属连词that、whether，关系代词：who, what, which, whom, whose, whatever, whoever, whomever, whichever；关系副词：when, where, how, why, however, whenever, wherever等。
That you don’t like him is none of my business.你不喜欢她不管我的事。
What he said is true. 他说的是真的。
Do you remember how he arrived almost at the end of the party?你记得他几乎是在宴会快结束时才到的吗？ This party's really where it's at, man! 啊，这个晚会真棒！Tell us how you fulfilled the heavy task ahead of schedule.告诉我们,你们是怎样提前完成这一艰巨任务的。
We have reason to believe that the fighting on the border may develop into a full-blown war. (喻)我们有理由相信边境上的冲突可能发展成一场全面战争。
He said that he would come. 他说他要来。
Whether the football game will be played depends on the weather.足球比赛是否举行将视天气而定。
表语从句用作表语的从句叫作表语从句，它位于主句中的连系动词之后。
引导表语从句的词有从属连词that、whether、as though(if)；关系代词who, what, which, whom, whose, whatever, whoever, whomever, whichever等；关系副词when, where, why, how, however, whenever, wherever等。
可以接表语从句的连系动词由be, look, remain, seem等。
That引导表语从句时，在口语中，间或可以省略。
The trouble is that we are short of money.困难是我们资金短缺。
That is why stone walls are used instead of fences around New England fields.这就是为什么在新英格兰用石头墙而不用栅栏的原因。
At that time, it seemed as if I couldn't think of the right word anyhow.当时,我似乎怎么也想不出一个恰当的字眼来。
宾语从句(object clauses)用作宾语的从句叫做宾语从句。
宾语从句的位置与陈述句基本结构中的宾语相同。
宾语从句可作谓语动词的宾语，也可以作介词和非谓语动词（动词不定式、动名词、分词）和某些形容词的宾语。
宾语从句可以由从属连词that whether、if，关系代词what, who, whose, which 和关系副词when、where、how、why等引导。
He said he wanted to go to town. 他说他想去城里。
I hope you'll be better soon.我希望你能很快好起来。
I’m so glad that you were able to come to this party.你能设法抽空出席这个交际会，我很高兴。
I know nothing about it except what I have read in the papers.除了在报上读到的以外,我对这件事一无所知。
Most of the Chinese people usually go to work on the bike except when it rains.除了雨天,大多数中国人一般都骑自行车上班。
He asked me whether she was coming. 他问我，她来还是不来。
同位语从句用作同位语的从句叫同位语从句。
它一般跟在抽象名词fact，idea，news，hope，belief，thought，truth，doubt，suggestion，warning, instruction，reason，information, question等之后，对这些名词进行说明或解释。
引导同位语从句的词除连词that，whether外，还有关系代词what, which, who, 以及关系副词how，when，where，why等。
It is a fact that smoking is a danger to health.吸烟危害健康，这是事实。
I have no idea what you mean.我一点儿也不明白你的意思。
He made the suggestion that we go by train. 他建议我们坐火车去。
There is no doubt that he is guilty. 毫无疑问，他是有罪的。
一、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：He judged that, because he was a child, he did not understand wineEveryone knew what happened and that she was worried.The reason lies in that she works harder than the others do.③that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/rep orted/ 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 W orld 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 doit 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。
