名词性从句在复合句中起名词作用的从句叫名词从句 (Noun Clauses）。
名词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、同位语等，因此根据它在句中不同的语法功能，名词从句又包括：主语从句、宾语从句、表语从句和同位语从句。
名词性从句中一律用陈述语序。
辨别下列名词性从句的类别：1.How the book will sell depends on its author.2.John said that he was leaving for London on Wednesday.3.The fact is that he has not been seen recently.4.The fact that he has not been seen recently disturbs everyone in his office.5.He will talk to us about what he saw in England.6.It is impossible that I go and attend the meeting.引导名词性从句的连词：1. 连接词：that (无词义，在句中不充当任何成分)if / whether (有词义“是否”，但不充当任何成分)2. 连接代词：who, whom, whose, what, which,（有词义，在句中充当主语、表语、宾语或定语）3．连接副词：when, where, why, how, （有词义，在句中充当状语）一．主语从句主语从句是在复合句中充当主语的从句，通常放在主句谓语动词之前或由形式主语it代替，而从句本身放在句子末尾。
1.主语从句位于主句谓语动词之前。
What matters most in learning English is enough practice.Where we shall have the meeting makes no difference.Whether the sports meeting will be held is not certain now.2.it 作形式主语代替主语从句，而真正的主语从句位于句末。
例如：It is a pity that you didn’t go to see the film.I t doesn’t interest me whether you succeed or not.3.主语从句谓语动词的单复数问题无论主语从句有多长，一般谓语动词用单数。
Where the English evening will be held has not yet been announced.What he wants to tell us is not clear.二．宾语从句宾语从句就是在复合句中作宾语的名词性从句，通常作谓语动词 (及物动词) 、介词、形容词的宾语。
1.作动词的宾语I heard (that) he joined the army.She did not know what had happened.I wonder whether you can change this note for me.She told me that she would accept my invitation.2.作介词的宾语Our success depends on how well we can cooperate(合作）with one another.You can give the book to whomever you like.3.作形容词(如sure,happy, glad, certain)的宾语I am afraid (that) I’ve made a mistake.I am sure (that) he will win the game.4. it 可以作为形式宾语it 不仅可以作为形式主语，还可以作为形式宾语而真正的宾语从句则放在句尾，特别是在带复合宾语的句子中。
例如：We thought it good news that the fog had finally gone.We find it necessary that we practice spoken-English every day.5. 否定前移若主句谓语动词为think, consider, suppose, believe, expect, 等，其后的宾语从句若含有否定意义，一般要把否定词转移到主句谓语上，从句谓语用肯定式。
例如：I don’t think the dress fits you well. 我认为这件衣服不适合你穿。
三．表语从句表语从句是在复合句中作表语的名词性从句，放在系动词之后，一般结构是“主语＋连系动词＋表语从句”。
可以接表语从句的连系动词有be, look, remain, seem等。
另外，常用的还有the reason is that… 和It is because 等结构。
1.表语从句位于系动词之后The reason why he is late for school is that he missed the early bus.But the fact remains that we are behind the other classes.The problem is whether the book will be published.2. as if, as though ,because 也可以引导表语从句。
It looks as if it is going to rain.It is because my car broke down on my way home.3.主语是advisem suggestion, order 等表示建议，要求，命令等的名词时，表语从句的谓语要用虚拟语气：(should) +动词原形，should 可省略。
He gave me a suggestion that I ( should )be calm now.四．同位语从句1.同位语从句的功能同位语从句就是在复合句中作名词的同位语的名词性从句。
同位语从句对于它前面的名词进一步解释，说明名词的具体内容，一般跟在fact,news,idea,truth,hope,problem, information, belief,thought, doubt,promise,question等抽象名词之后。
The news that we won the game is exciting.I have no idea when he will come back home.2.同位语在句子中的位置当主句的谓语动词较短，而同位语从句较长时，同位语从句常常后置。
He got the news from Mary that the sports meeting was put off.3.同位语从句和定语从句的区别：引导定语从句时，that作为关系代词，它在从句中必须充当句子成分，在从句中作宾语时可以省略；that引导同位语从句时，起连词的作用，没有实际意义，不充当句子成分，一般不能省略。
试比较下面两个例句:The news that our football team won the natch was encouraging.（that引导同位语从句，从句不缺任何成分，不能省略）The news that we heard on the radio was not true.（that引导定语从句，作宾语，可以省略）一、划出下列各句含有的名词性从句，并指出是名词性从句中的哪一种：1.What he wants is a book.2.It is so nice that we can learn this grammar point together.3.I’m so glad that I can make friends with you.4.This is why he did it.5.Do you agree to the suggestion that we (should) have a trip in Tibet?6.That he wants a book is certain.7.I suggested just now we (should) take part in this activity.8.Whether you like him or not doesn’t matter too much.9.He doesn’t know whether you can sing it well.10.The problem is whether you can sing it well.11.The problem whether it is right or wrong has not been decided.12.Please tell me who your monitor is.二．辨别下列从句是定语从句还是名词性从句1.We heard the news that our team had won.2.We must face the fact that we had spent all our money.3. The news that he told me yesterday was false.4. I have no doubt that he will come soon.5. The fact is that we have spent all our money.五．名词性从句的几个重难点1. that 和what，which 的区别：that 和 what 都可引导所有的名词从句。
但是，what除起连接作用外，还在名词性从句中充当成分，可在从句中做主语、宾语、定语或表语，表示疑问“什么”或者表示“…的人，/地方/东西”。
而that 在名词性从句中只起连接作用，不充当任何成分，无意义。
which在从句中也可以做主语、宾语、定语或表语，但指的是在某个特定范围中的哪一个，哪一些。
例：It is uncertain _____side effect the medicine will bring about, although about two thousand patients have taken it.A．that B．what C．how D．whether答案：B 考点：本题考查主语从句的引导词。