名词性从句与定语从句的区别

名词性从句

在句子中起名词作用的句子叫名词从句 (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、介词宾语等，因此根据它在句中不同的语法功能，名词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。

定语从句

定语从句是由关系代词和关系副词引导的从句，其作用是作定语修饰主句的某个成分，定语从句分为限定性和非限定性从句两种。状语从句分为时间状语从句，结果状语从句，让步状语从句，原因状语从句，条件状语从句以及行为方式状语从句。名词从句包括主语从句，宾语从句，表语从句和同位语从句及there be句型

名词性从句包括主语从句、宾语从句、表语从句和同位语从句。引导名词性从句的连接词按其在从句中所起的作用分为：

1）连接代词：who(-ever), what(-ever), which(-ever), whom(-ever), whose

2）连接副词：when, where, why, how

3）连接词：that, whether, if

连接代词和连接副词在从句中充当一定的句子成分，而连接词在从句中不充当句子成分，只起连接作用。

1．主语从句

在主句中充当主语的从句叫主语从句，它位于主句的谓语动词之前。但实际使用中常用it作形式主语，而把主语从句移到主句之后。例如：

Who will go makes no difference.

It makes no difference who will go.

That she was able to come made us very happy.

It made us happy that she was able to come.

注意：由what, whoever, whatever, whichever引导的主语从句一般不后置。

2．表语从句

位于主句中系动词之后，在主句中充当表语的从句叫表语从句。例如：

One advantage of living in the country is that one can get close to nature.

His mother was ill and he had to look after her. That was why he was late.

表语从句常见于be动词之后，有时见于look之后；引导表语从句的连接词除前面所列的常用词之外，还可由because, as if/though引出。例如：

He was late. That was because he had to look after his sick mother.

(=The reason was that he had to look after his sick mother.)

It looks as if/though it is going to rain.

They looked as if/though they had been friends for many years.

3．宾语从句

在主句中位于及物动词之后或少数介词之后、充当主句宾语的从句叫宾语从句。宾语从句中的that通常可以省略。例如：

I doubt whether/if he will be against the idea.

She will write a book on how young mother should raise their babies.

I know nothing about him except that he lives next door.

当及物动词后跟两个(或两个以上)的宾语从句时，只有第一个that可以省去，后面从句中的that通常不省去。如：

He said (that) the text was very important and that we should learn it by heart. 跟在一些表示情感意义的形容词（如afraid, glad, happy, pleased, sorry, anxious, worried, surprised,

disappointed等）或确信意义的形容词（如certain, sure 等）后的从句通常也被当作宾语从句对待，其中that也可以省略。例如：

I’m not sure whether/if I can pass the exam successfully.

如果主句的谓语是make, find, feel, believe, think, suppose, consider, see to等常带有宾语补足语的动词，则通常在这些词后用it作形式宾语，而把宾语从句置于宾语补足语之后，其结构通常是“动词+it+宾补+宾语从句”。例如：

He thought it a pity that he missed the film.

We find it necessary that we (should) practise spoken English every day.

4．同位语从句

跟在名词后面、进一步说明该名词的具体内容的从句叫同位语从句。可以带同位语从句的名词主要是一些可加进具体内容的、表示信息、思想等概念的抽象名词，如news, fact, idea, hope, belief, truth, promise, thought,

fear, doubt, possibility, order, suggestion, proposal等。同位语从句与其前面的名词是同等关系，引导同位语从句最常用的是that，that在从句中不充当任何成分，只起连接作用，一般不能省略。例如：

We are surprised at the fact that the children did it all on their own.

I made a promise that if anyone set me free, I would make him very rich.

They expressed the hope that we would go and visit Germany again.

that引导的同位语从句与定语从句的区别：

The suggestion that the students (should) have plenty of exercise is very good.

The suggestion (that/which) he raised at the meeting is very good.

对比发现上句中的that只起连接作用，在从句中不充当任何成分， 因此它引导的是同位语从句，其中that不能省略；下句中that不仅起引导作用，同时在从句中还充当了动词raised的宾语，因此它是定语从句，此时that可用which代替，又因其在定语从句中充当宾语，故又可省略。

名词性从句的难点把握

1．由whoever/whatever/whichever/whomever引导的名词性从句

这些词引导的名词性从句相当于带有定语从句的名词词组：

whoever=anyone who…“任何……的人”；whomever是whoever的宾格形式

whatever=anything that… “任何……的物”

whichever=any … that… “任何……的（已知范围内的或上文提到过的）人或物”

它们可以用来引导主语从句，例如：

Whoever leaves the room last ought to turn off the light.

=Anyone who leaves the room last ought to turn off the light.

Whatever he had was seized by the German soldiers.

=Anything that he had was seized by the German soldiers.

Whichever of you comes in first will receive a prize.

=Any one of you who comes in first will receive a prize.

这些词还可以用来引导宾语从句，例如：

You can just say whatever comes to your mind.

=You can just say anything that comes to your mind.

Take whichever seat you like.

=Take any seat that you like.

You may choose whoever/whomever you’d like to go with.

=You may choose anyone who you’d like to go with.

( 注：whoever在主句中作choose的宾语，在从句中又充当go with的宾语，因此可用宾格的whomever来代替 )

She would like to make friends with whoever shares her interest.

=She would like to make friends with anyone who shares her interest.

（注： whoever在主句中作介词with的宾语，但在从句中又充当谓语动词shares的主语，因此不能用whomever代替 ）

关于—ever等词引导让步状语从句的用法可参阅本章第三节“状语从句”。

2．名词性从句中的what和that

what和that的选用一直是学生学习的一个难点，正确选择的关键是看该从句结构是否相对

完整、是否缺少主语、宾语或表语等成分而定。例如：

What he said at the meeting surprised everybody present.

That he said nothing at the meeting surprised everybody present.

The problem is what we should do to protect the earth.

The fact is that we should do something to protect the earth.

比较上面两组句子，不难发现，what在句中不仅引导从句，同时它本身在从句还充当了宾

语的作用；没有了what，从句结构就不完整；而that只起引导从句的作用，本身在从句中不充当任何成分，that引导的是一个结构相对完整的陈述句。

3．名词性从句中的whether和if