名词性从句 定语从句 状语从句

1．名词性从句定语从句状语从句

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，名词性从句厅分为主语从句、表语从句、宾语从句和同位从句。

（一）引导名词性从句的连接词

1、连接代词：who whose whom what which。有词义，在从句中担任成分，如主语、表语、宾语、或定语等。

2、连接副词：when where why how。有词义，在从句中担任成分，作状语。

3、从属连接词：that whether if as if。that 无词义，在从句中不担任成分，有时可省略；if whether as if 虽有词义，但在从句中不担任成分。注意：连接代词与连接副词在句中不再是疑问句，因而从句中谓语不用疑问式。连接代词与连接副词在从句充当句子成分，连接词（从属连词）whether 和if（是否），as if（好象）在从句中不充当句子成分，只起连接作用。根据句义，如果连接代词与连接副词，whether、if 和as if 都用不上时，才用that 作连接词（that 本身无任何含义）。

（二）主语从句

1、主语从句在复合句作主语。e.g. Who kept the door open all night was unkonwn.

2、用it 作形式主语，主语从句放在句末。e.g. It doesn‟t matter so much whether you will come or not.

3、that 引导主语从句时，不能省略。e.g. That he suddenly fell ill last week made us surprised. It made us surprised that he…（三）表语从句

1、表语从句在复合句中作表语，位于系动词之后。e.g. The question was who could go there.

2、引导表语从句的连接词that 有时可省去。 e.g. My idea is that we can get more comrades to help in the work.

（四）宾语从句

1、宾语从句在复合句中作宾语。引导宾语从句的连词that 一般可省略。e.g. I hope that everything is all right.

2、介词之后的宾语从句，不可用which 或if 连接，要分别用what 或whether。e.g. I‟m interested in whether you‟ve finished the work.. I‟m interested in what you‟ve said.

3、whether 与if 都可以引导宾语从句，常可互换。但下面情况不能互换。①宾语从句是否定句时，只用if，不用whether。

e.g. I wonder if it doesn‟t rain. ②用if 会引起误解，就要用whether。e.g. Please let me know whether you want to go.（此句如果把whether 改成if，容易当成条件句理解）③宾语从句中的whether 与or not 直接连用，就不能换成if；不直接连用，可换。e.g. I don‟t know whether or not the report is true. I don‟t know whether/ if the report is true or not. ④介词后的宾语从句要用whether 引导。whether 可与不定式连用。whether 也可引导主语从句、表语从句、同位语从句，还可引导让步状语从句，以上均不能换成if。但引导条件从句时，只能用if，而不能用whether。e.g. It depends on whether we have enough time. They don‟t know whether to go there. Please come to see me if you have time.

（五）同位语从句

同位语从句在句中作某一名词的同位语，一般位于该名词（如：news fact idea suggestion promise 等）之后，说明该名词的具体内容。 e.g. I have no idea when he will be back. The fact that he had not said anything surprised everybody.

名词性从句详解：

主语从句、表语从句、宾语从句、同位语从句在复合句中起名词的作用，这四种从句合称名词性从句。它们在主句中充当主语、表语、宾语或同位语，都不能用逗号与主句分开。注：句中划线部分为从句

■主语从句

1、定义：先找到句子的谓语，主句的谓语前面的从句，叫做主语从句。Why he left wasn‟t important.wasn‟t 是主句的谓语动词，why he left 做主语从句That she became an artist may have been due to her father‟s influence.may have been due 是主句的谓语动词，that she became an artist 做主语从句

2、借助形式主语it，主语从句放在后面①由that 引导的主语从句可以放在主语的位置，这时that 不可以省略。例如：That prices will go up is certain. that 主语从句放在句首的情况不是很常见，绝大部分主语从句都借助形式主语it，主语从句放在后面。It is strange that he knows nothing about it. It is a pity that he can‟t swim. It happened that he wasn‟t in that day. It is said that there has been an earthquake in India. 在口语中，用it 做形式主语时，主语从句的that 可以省略。②wh-疑问词引导的主语从句，可以放在句首第一组，也可以借助形式主语it 第二组。第一组：When he‟ll be back depends much on the weather.How it was done was a mystery.Whether we‟ll succeed remains to be seen.第二组：It is uncert ain whether the game will be held.It‟s a puzzle how life began.It doesn‟t matter much where we live.Is it known where he went？

■宾语从句1、定义：及物动词第一组和介词第二组的后面可以接从句做宾语，叫做宾语从句。第一组I guessthat we‟ll leave soon.He asked when we would be in London.She informed me that she was to send for it the next day.that 可以省略I‟ll tell you what I read in today‟s paper.第二组I‟ll find out whether she‟s interested in going.Can you give us a description of what has happened. She was shocked by what she had seen. 2、借助形式宾语it，that 引导的宾语从句放在后面。I‟ve heard it said that you have won a scholarship. 分析：it 在句中做形式宾语，said 做宾语补足语，that you have won a scholarship 是真正的宾语。She has seen to it that all the children are well taken care of. it 分析：在句中做形式宾语，that all the children are well taken care of 是真正的宾语。

■表语从句1、定义：系动词的后面可以接句子做表语，叫做表语从句。The fact is that she never liked him. That is not what I meant. The question is who is responsible for what has happened. She is no longer what she used to be. 2、注意：①The reason Hollywood was a good place for making movies was that the sun shines there every day. 分析：the reason 做主语时，表语从句用that 引导。②引导表语从句的that 一般不省略。

■同位语从句1、定义：有些名词的后面可以跟that 引导的从句，说明这个名词的内容，这样的从句叫做同位语从句。所以，只有可以有内容的名词才可以接同位语从句，例如：fact，message，idea，possibility，conclusion，thought，news，order，report，rumor 等等。that 在从句中不做成分，但是不能省略。He had the feeling that he would not see her again.I‟ve