名词性从句名词性从句是在句子中起名词作用的句子。

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。

连接词引导名词性从句的连接词可分为三类：1.连词：that （本身无意义。

引导单一的宾语从句时that常可省略，但引导主语从句、表语从句、同位语从句时that通常不被省略）whether,if （均表示“是否”）as if ,as though （均表示“好像”，“似乎”）◆以上在从句中均不充当任何成分2.连接代词：what/ whatever, who/ whoever, whom/ whomever, whose/whosever, which/whichever.有词意，在从句中充当主语，宾语，表语，定语等。

3.连接副词：when/ whenever, where/ wherever, how/ however, why.有词意，在从句中充当状语。

主语从句作句子主语的从句叫主语从句。

主语从句通常由连词that，whether，和连接代词what，who，which，whatever，whoever以及连接副词how，when，where，why等词引导。

that 在句中无词义，只起连接作用；连接代词和连接副词在句中既保留自己的疑问含义、又起连接作用，在从句中充当一定的成分。

主语从句后的谓语动词一般用单数形式。

例如：What he wants to tell us is not clear. 他要跟我们说什么，还不清楚。

Who will win the match is still unknown. 谁能赢得这场比赛还不得而知。

It is known to us how he became a writer. 我们都知道他是如何成为一名作家的。

Where the English evening will be held has not yet been announced. 英语晚会将在哪里举行，还没有宣布。

有时为避免句子头重脚轻，常用形式主语it代替主语从句作形式主语放于句首，而把主语从句置于句末。

常用句型如下：用it 作形式主语的结构(1)It is ＋名词＋从句It is a fact that … 事实是…It is an honor that …非常荣幸It is no wonder that 难怪…(2) It is ＋形容词＋从句It is natural that… 很自然…It is strange that… 奇怪的是…(3) It is ＋不及物动词＋从句It seems that… 似乎…It happened that… 碰巧…It appears that… 似乎…It occurre d to me that…我突然想起……(4) It ＋过去分词＋从句It is reported that… 据报道…It has been proved that… 已证实…It is said that… 据说…另注意在主语从句中用来表示惊奇、不相信、惋惜、理应如此等语气时，谓语动词要用虚拟语气“(should) +do”，常用的句型有：It is necessary (important, natural, strange, etc.) that …It is suggested (requested, proposed, desired, etc.) that…众所周知的几种表达方式（1）It is known to us that.（2）As is known to us.（3）what is known to us is that.【注意】与强调句结构的区分：It is/was+被强调部分+that/who+句子其它部分。

It is John that broke the window. 是John打碎的窗户。

（强调句型）宾语从句宾语从句就是在复合句中作宾语的名词性从句，通常放在主句谓语动词 (及物动词) 或介词之后。

I.位置1．作动词的宾语(1) 由that引导的宾语从句(that在句中不担任任何成分，在口语或非正式的文体中常被省去，但如果从句是并列句时,第二个分句前的that不可省。

), 例如：I heard that be joined the army. 我听说他参军了。

(2) 由what, whether (if) 引导的宾语从句，例如：She did not know what had happened. 她不知道发生了什么。

I wonder whether you can change this note for me. 我想知道你是否能帮我改一下笔记。

(3) 动词＋间接宾语＋宾语从句。

例如：She told me that she would accept my invitation. 她对我说她会接受我的邀请。

2. 作介词的宾语Our success depends upon how well we can cooperate with one another. 我们的成功取决于我之间的合作。

3. 作形容词的宾语I am afraid (that) I’ve made a mistake.我恐怕我已经犯了一个错误。

注意：that 引导的从句常跟在下列形容词后作宾语：anxious, aware, certain, confident, convinced, determined, glad, proud, surprised, worried, sorry, thankful, ashamed, disappointed, annoyed, pleased, hurt, satisfied, content 等。

也可以将此类词后的that 从句的看作原因状语从句。

II. it 可以作为形式宾语1．动词make, find ,think,feel,consider,believe等后面有宾语补足语的时候，则需要用it做形式主语，而将that宾语从句后置。

I think it necessary that we take plenty of hot water every day.我认为每天多喝开水是有必要的。

I feel it a pity that I haven't been to the get-together.我没去聚餐，感觉非常遗憾。

2.动词＋it＋when / if 从句.常见于appreciate, enjoy, like, dislike, love, hate,prefer等少数动词之后。

We would much appreciate it if you could do us that favour.要是你们能帮我们这个忙，我们将非常感激。

I'd prefer it if I didn't have to finish the work.要是我不必完成那项工作，那就太好了。

3.动词+ it + that从句。

常见于like, take, have, put等少数动词之后。

I take it that they will succeed sooner or later.我认为他们迟早会成功的。

The newspapers have it that some Japanese firms have gone bankrupt.报上说一些日本商号破产了。

4.动词 + it + 介词短语 + that从句。

常见于bring it to one's attention;owe it to sb; take it for granted 等结构中。

I owe it to you that I finished my work in time.多亏有你我才及时完成了工作。

Don't take it for granted that they will support you.不要想当然地认为他们会支持你。

5.动词 + 介词(短语) + it + that从句。

常见于answer for, depend on, rely on, insist on, see to, 等结构中。

I'll see to it that everything is ready in time.我将负责按时做好一切准备。

You may depend on it that Tom will help you with your English.你放心，汤姆会帮助你学英语的。

6.动词+ it +过去分词+从句。

常见于几个可以带过去分词作宾语补足语的动词之后。

I heard it said that that factory was founded in 1995.我听说那家工厂是1995年创建的。

They haven't made it known where the meeting is to take place.他们没有宣布会议在哪里召开。

III. 否定的转移若主句谓语动词为think, consider, suppose, believe, expect, fancy, guess, imagine 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 this dress fits you well. 我认为这件衣服不适合你穿。

I don' t believe he will come. 我相信他不会回来。

IV宾语从句中虚拟语气的运用注意：在demand、order、suggest、insist, desire, request, command, 等表示要求、命令、建议、等意义的动词后，宾语从句常用“（should）+ 动词原形”。

I insist that she (should) do her work alone. 我坚持要她自己工作。

The commander ordered that troops (should) set off at once. 司令员命令部队马上出发。

表语从句在复合句中，位于系动词之后作表语的从句叫表语从句。

引导表语从句的关联词与引导主语从句的关联词大致一样，表语从句位于系动词后，有时用as if引导。

其基本结构为：主语+ 连系动词+ that从句1.that 引导表语从句，无词义，只起连接作用，不可省。

2.连系动词可为be,look,seem,sound,appear等。