英语语法之名词性从句

mxb08 2015-06-24

展开全文

名词性从句相当于名词，一个从句在整个句子中充当名词的作用，它可以作为主句的主语、表语、宾语和同位语。

名词性从句主要分为四种：主语从句，表语从句，宾语从句，同位语从句。

1. Who will win the match is unknown.

2. I want to know what he has told you.

3. The fact is that he had won the game.

4. The news that we won the game is exciting.

(一)宾语从句

宾语从句在复合句中做及物动词的宾语，或用作介词和某些表示心理活动的形容词后作宾语，或是用it 作为形式宾语代表宾语从句。
例:1. I think that it will be of no use.
2. It depends on whether the boss will agree to you or not.
宾语从句的连接词：
that,（常用且一般可省略）who, what, whether/if（是否）which, whoever, whatever ，when, where, how, why.
(连接词的选择要看从句的具体意思需要)
例：1. I know that you are a teacher.
2. I wonder if/ whether you are Mr Li.
3. Do you know what I will do next?
4. I can guess which team will win.
5. I don’t know when he will come.
6. I don’t know where he has gone.
7. They don’t know how they should help me.
8. Please give the book to whoever likes it.
Attention:
①★宾语从句的语序一定是正常的语序，即陈述句的语序，先主语后谓语。
I don’t know who are you. (X)
I don’t know who you are. (∨)
②★从句的时态需跟主句相配合。主句为一般现在时，从句可根据需要选择各种时态；
主句为一般过去时时，从句通常用过去的时态。
③★介词后的宾语从句，引导词一般不用which，if，that，但可用what（常用，常常是充当从句的主语，宾语或表语），how, whether等引导。
④★that在所有的名词性从句中都不充当成分，在宾语从句中that可以省略。

（二）主语从句

1.Whose watch was lost is unknown.
2.What we need is time.
3.Whom we must study for is a question of great importance.
4.Whether we will go for an outing remains unknown.
5.That he finished writing the composition surprised us all.
1.主语从句的连接词：
1）从属连词（从句中不充当成分，只起连接作用）：that，whether等.
that 引导主语从句只起引导作用，本身无意义，在主语从句中不充当任何成分，但不能省略。注意: 已确定的事由that引导;没决定的事由whether引导.
That he will come is certain.
Whether it will please them is not easy to say.
2)连接代词（在从句中充当主语，宾语，或表语）who ，what ，which, whatever, whichever, whoever
What seems easy to some people seems difficult to others.
Which side will win is not clear.
Whoever comes is welcome.
Whatever I have is yours.
3)连接副词 when（从句中作时间状语） where （从句中作地点状语）
how （从句中作方式状语） why（从句中作原因状语）
Why he did it remains a mystery.
When they will start is not known yet.
How he became a great scientist is known to us all.
2. 主语从句后置!
为了避免主语冗长,句子头重脚轻,经常用it作形式主语,主语从句放在后面作真正的主语.
如： 1）. That we shall be late is certain.
-- It’s certain that we shall be late.
2）. That the earth is round is known to all.
-- It’s known to all that the earth is round.
用it作形式主语的that从句有以下几种不同的搭配：
1.It + be + 形容词＋ that从句
2.It + be + -ed分词＋ that从句
3. 主语从句需注意的问题
1）.“if” 通常不能引导主语从句，要用“whether”引导。
2）.主语从句中用陈述句语序
3）.主语从句的 “that” 一般不能省。That price will go up is certain.
4）.主语从句后谓语动词用第三人称单数
That they haven’t phoned is strange.
5）.主语从句在句首时，必须由连接词引导，不能省略这些连接词；但是如果用it做形式主语，而把主语从句放在句末时，从属连词that可以省略。
6）.如果主语从句放在句首，不能用if引导，但是如果用it 做形式主语，而把主语从句放在句末时，也可以用if引导.
误：If Mary really heard him is really doubtful.
正：It was doubtful if Mary really heard him.
7）.用于It is important / natural / necessary /
impossible that...句型中, 主语从句谓语动词用“（should） + 动词原形”的形式, should可以省略。
例： It is imporant we (should) believe him.
8）. 在it + be + suggested/ advised/ required/ ordered/ requested/ insisted that…句型中
从句谓语动词也用“（should） + 动词原形”的形式.
例： It is suggested that we (should) go there by bus.
9）. what 与that 在引导主语从句时的区别
what 引导主语从句时在句时在从句中充当句子成分，如主语．宾语．表语，而that 则不然。例如：
A： What you said yesterday is right.
What在此引导主语从句,又做said的宾语
B： That she is still alive is a consolation。
That 只起连接作用,不做成分

（三）表语从句

1.定义：放在be动词和系动词后的从句。
The question is who will do it.
2.可接表语从句的连系动词有be（is, am, are, was, were）, look, seem, sound, appear，remain, become, get等。
China is no longer what she used to be.
The question remains whether they will be able to help us.
At that time, it seemed as if I couldn't think of the right word.
3.表语从句的引导词
1）. 从属连词whether, as, as if / though引导的表语从句.if不能引导表语从句。
He looked just as he had looked ten years before.
It sounds as if someone is knocking at the door.
2）. because, why引导的表语从句
That’s because he didn’t understand me.
That’s why he got angry with me.
The reason why I was sad was that he didn't understand me. （…的原因是…）
3）. 连接代词who, whom, whose, what, which, whoever, whatever, whichever连接副词 where, when, how, why
The problem is whom we can get to replace her.
The question is how he did it.
That was what she did this morning on reaching the classroom.
This is where our problem lies.
4）. 从属连词that。that在表语从句中不充当句子成分，没有任何意义, 也不能省略。
The trouble is that I have lost his address.
4、使用虚拟语气的表语从句
在表示“意愿，建议、劝告、命令”含义的名词后的表语从句，谓语动词需用“should+动词原形” should可省略。
常见的这些名词有：advice, suggestion, order, proposal, plan, idea等。
My suggestion is that we (should) start early tomorrow.
5、表语从句的应注意的问题：
1）. That在表语从句中既不充当成分，也没有任何意义
The fact is that he hasn’t yet recover from illness.
2）. What 在表语从句中充当主语、宾语/表语表示什么，什么样子，/所……
的（人或事）.
A. The question is what caused the accident.
B. That mountain is no longer what it used to be
3）. Which 在引导表语从句时,常充当定语, 表语表示其中哪一个
I read about it in some book or another,but what I don’t know is which (book) it is.
4）. whether在表语从句中表“是否”,不充当句子的成分。if 不能引导表语从句。
What the doctor really doubts is whether my mother will recover from the serious disease soon.
5）. 当主句的主语为reason,或者是由why引导的从句时,与它们相关的表语从句用
that来引导，而不能由because引导; because 引导表语从句时只能用于It/That/This is /was because…那是因为…
It/That/This is /was why…那就是为什么…
The reason ( why…) is/was that.. …的原因是…

（四）同位语从句

1. 定义：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。
2.同位语从句的功能
同位语从句对名词进一步解释，说明名词的具体内容，这些名词一般是抽象名词，常用名词有fact, news, hope, truth, idea, suggestion, thought, question, order, problem, belief, doubt, fear, result, information, opinion, demand, wish，promise, possibility, message,等.
常用引导词：that （常用不可省略）, who, when, where, why, how, whether等。
3.同位语从句的引导词
1）. 由that引导，在从句中不充当任何成分，只起引导作用，不可省略，也不能用which代替。如：
The fact that you have passed the exam is true.

比较宾语从句：

1）don’t know (that) you have passed the exam.
2）.由whether 引导，“是否”，
注意：同位语从句中表示“是否” 的意思时，不能用if。
如：The problem whether we should visit her has been settled.(不能用if)
3）.由who, when, where, how 等引导
如：①I have no idea who will go with me.
② We haven’t solved the problem how we should go there.
③ We haven’t solved the problem where we are going to spend the weekend.
④we have no idea when we will begin our holiday.

※同位语从句与定语从句的相似之处

1、两种从句都可以译成定语
2、两种从句都可以用that引导
The news that our team has won the final match is encouraging.(同位语从句)
我们队取得决赛胜利的消息令人鼓舞。
The news that you told us is really encouraging.(定语从句)
你告诉我们的消息真的令人鼓舞。

※同位语从句与定语从句的不同之处

1、从句的作用不同：同位语从句用来进一步说明前面名词的内容；定语从句用来修饰、限定前面的名词。
The news that our team has won the final match is encouraging. （从句说明“消息”的内容：我们队取得了决赛胜利。）
The news that you told us is really encouraging.
（从句对“消息”加以限定：是你告诉我们的, 而非来自其他渠道。但消息是什么却不得而知。）
2. 引导从句的关联词that的功能不同:
①在that引导同位语从句中，从句是个完整的句子, that只是一个连接词, 不充当任何成分; that不能省略，不能用which代替。
Dad made a promise that he would buy me CD player. (that 不充当任何成分)
②在that引的定语从句中，从句不完整，缺少主语或宾语that是关系代词, 既指代先行词又在从句中充当主语或宾语，充当宾语时可以省略，可换成which.
Dad made a promise that excited all his children. (that指代promise, 又在从句中充当主语.)
③定语从句不可用what, how, whether, 来引导，而同位语从句的关连词除了that 外，还可根据词义使用其它疑问代词或疑问副词，如who, when, where, how, whether等。

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