【编者按】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、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 will go is not important.
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.
(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.
练习：名词性从句
一、判断下列各句哪句含有名词性从句，并指出是什么从句：
1. China is no longer what it used to be.
2. The truth that the earth turn around the sun is known to all.
3. It was snowing when he arrived at the station.
4. How he persuaded the manager to change the plan is interesting to us all.
5. The news that they had won the game soon spread over the whole school.
6. The news that you told me yesterday was really disappointing.
7. That is where Lu Xun used to live.
8. He spoke as if he understood what he was talking about.
9. Do you remember the teacher who taught us English at middle school?
10. I wonder why she refused my invitation.
二、用适当的连词填空：
1. I can't decide ____________ dictionary I should buy.
2. That's ____________ he refused my invitation.
3. I am very interested in ____________ he has improved his pronunciation in such a short time.
4. ____________ we need is more time.
5. The fact ____________ she had not said anything at the meeting surprised everybody.
6. ____________ and ____________ they will meet has not been decided yet.
7. Please tell me ____________ you are waiting for.
8. Is that ____________ you are looking for?
9. Would you please tell me ____________ the nearest post office is?
10. I don't know ____________ he will agree to the plan or not.
三、选择填空：
1. Do you see _____ I mean?
A. that B./ C. how D. what
2. Tell me_____ is on your mind.
A. that B. what C. which D. why
3. We must stick to _____ we have agreed on.
A. what B. that C. / D. how
4. Let me see _____.
A. that can I repair the radio B. whether -I can repair the radio
C. I can repair the radio D. whether can I repair the radio
5. Keep in mind _____.
A. that the teacher said B. what did the teacher say
C. that did the teacher say D. what the teacher said
6. Could you advise me _____?
A. which book should I read first B. what book should I read first
C. that book 1 should read first D. which book I should read first
7. He was criticized for _____.
A. he had done it B. what he had done C. what had he done D. that he had done it
8. Would you kindly tell me _____?
A. how can I get to the Beijing Railway Station
B. how I can get to the Beijing Railway Station
C. where can I get to the Beijing Railway Station
D. whether can I get to the Beijing Railway Station
9. Mrs. Smith was very much impressed by _____.
A. what had she seen in China B. that she had seen in China
C. what she had seen in China D. which had she seen in China
10. We took it for granted ___
A. that they were not coming B. that were they not coming
C. they were coming not D. were they not coining
11. I really don't know _____
A. I should do next B. what should I do next
C. what I should do next D. how I should do next
12. I'm afraid _____.
A. the little girl will have to be operated on
B. that will the little girl have to operate on
C. the little girl will have to operate on
D. that will the little girl have to be operated on
13. She walked up to _____ .
A. where did I stand B. where I stood
C. I stood there D. where I stood there
14. Can you tell me _____?
A. who is that gentleman B. that gentleman is who
C. who that gentleman is D. whom .is that gentleman
15. We'll give you _____.
A. that do you need B. what do you need
C. whatever you need D. whether do you need
16. They want us to know _____ to help us.
A. what can they B. what they can C. how they can D. how can they
17. We must put _____ into practice.
A. what we have learned B. that we have learned
C. that have we learned D. what have we learned
18. Did she say anything about _____?
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