高中英语语法主语从句讲解及练习

名词性从句 ---------主语从句
一、名词性从句概述：
在句子中起名词作用的各种从句统称为名词性从句。
根据它们在句中的语法作用，这类从句又可分为主语从句、同位语从句、表
语从句和宾语从句。
二、主语从句定义：
在句中起主语作用的从句称为主语从句。
引导主语从句的连接词主要有：单纯连词（that, whether if）、连接代词(what,
whatever, who, whoever, whom, whose, which, whichever等)和连接副词(when,
where, why, how, whenever, wherever, however等)。

1) that引导的主语从句
（1） 由连词that引导的主语从句:引导词that无含义在句中不做成分不可以省。
例如：That you will win the medal seems unlikely.你能得奖看起来不大可能。
That light travels in straight lines is known to all. 众所周知，光沿直线传播。
That you don’t like him is none of my business.你不喜欢他不管我的事。
（2）形式主语it替代主语从句位于句首，that引导真正的主语从句会放到句子
的后面。 常用的句式主要有如下几种：
+ 系动词+形容词+that从句。
如：
It is necessary that … 有必要……
It is clear that … 很清楚……
It is likely that … 很可能……
It is important that … 重要的是……
类似的形容词还有：strange; natural; obvious; true; good; wonderful; possible;
unlikely; quite; unusual; certain; evident; worth-while; surprising; interesting;
astonishing, etc.
例如： It was really astonishing that he refused to talk to you.
It is essential that he should be here by the weekend.
It seems obvious that we can not go on like this.
It is necessary that you （should）master the computer.
It is important that a student learn English well.
It’s clear that they badly need help.
It is likely that a hurricane will arrive soon.
知识拓展：在“
It is necessary importantsurprisi ngstrangeunthinkableunbelievableincredible+that
从句”这类主语从句结构中，从句中谓语动词常用“（should）＋动词原形”，形
式，即要用虚 拟语气,should 可省略。
例如：
It is necessary that a college student (should ) master one or two foreign languages.
大学生掌握一两门外语是有必要的。
It is strange that you (should) trust Jane.
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很奇怪你竟然相信简。
另外，需要注意的是，it作形式主语代替主语从句时 ，要注意和as引导的定语
从句的区别。试比较：
It was reported that the US was under the terrorist attack.
As was reported, the US was under the terrorist attack.

（2）
常见用it作形式主语的复合句结构

2. It +系动词 +名词+ that从句
如：
It is a fact that… 事实是……
It is good news that … ……是好消息
It is a question that … ……是个问题
It is common knowledge that … ……是常识
类似的名词还有：a pity；a wonder；a good thing； no wonder； surprise等。
例如：
It is a mystery to me how it all happened.
It is common knowledge that the whale is not a fish.
It is no surprise that Bob should have won the game.
It’s a pity that you missed the film.
3. It +be +动词的过去分词+that从句
如:
It is said that … 据说……
It is reported that … 据报道……
It has been proved that … 已证明……
It must be proved that… 必须指出……
类似的过去分词还有：known; estimated; expected; believed; thought; hoped; noted;
discussed; required; decided; suggested; demanded; made clear; found out,etc.
例如：It is thought that he is the best player.
It is estimated that the vase is 2000 years old.
It has not been made clear when the new road is to be opened to traffic.
It is said that he was killed in the earthquake.
4. It+特殊词+that从句。
如： It seems （happened appears doesn’t matter makes no difference
occurred …）that …
如：
It seems that they will win the game.
It makes no difference whether he will attend the meeting or not.
It does not matter if I missed my train.
It happened that I saw him yesterday.
2) 用连词 whether 引导的主语从句
whether有含义“是否”在句中不做成分不可以省。
注意：引导主语从句，不能用if，只能用whether。
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例如：
Whether you like him or not is none of my business.
Whether we will hold a party in the open air tomorrow depends on the weather.
Whether she is coming or not doesn’t matter too much.
3) 用连接代词引导的主语从句

在由连接代词who, whose, whom, which, what, whoever, whomever, whichever,
whatever引导的名词性从句中，
其连接代词在句中起名词性作用，担当一定成分.
例如：
What you need is more practice.
What I want to know is this.
Whatever we do is to serve the people.
注：whatever whoever的功用
whatever, whoever在主语从句中不含疑问意义。它引导主语从句，并在从句中作
主语、宾语、表语等。
whatever = anything that; whoever = anyone who。要注意和whatever, whoever引导
的让步状语从句的区别。
如：
Whoever breaks the law should be punished. （主语从句）
（ ＝Anyone who breaks the law should be punished. ）
Whoever breaks the law, he should be punished. （让步状语从句）
（ ＝No matter who breaks the law, he should be punished. ）
4）用连接副词引导的主语从句
用连接副词when, where, why, how, whenever, wherever, however等引导的主语从
句从句(其连接副词有含义,在句中作状语。)
例如:Where we should leave it is a problem.
When they will come hasn’t been made pubic.
温馨提示：如果主语从句是由连接代词what, whatever, whoever等引导的，表示
的是一个具体的东西或人时，这样的主语从句不能用it作形式主语。
What is worth doing is worth doing well.
Whatever was said here has left us much too think.
Whoever comes will be welcome.

1）随堂练习
1. It doesn’t matter _________ you turn right or left at the crossing---both roads lead
to the park.
A. whether B. how C. if D. when
2. It suddenly occurred to him ________ he had left his keys in the office.
A. whether B. where C. which D. that
3. ---- We’ve only got this small bookcase. Will that do?
---- No, _________ I am looking for is something much bigger and stronger.
A. who B. that C. what D. which
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4. It doesn’t matter ________ you pay by cash or credit card in this store.
A. how B. whether C. what D. why
5. ________ the polluting factory will be removed from the city is, in fact, ________
the citizens are glad to see.
A. That; as B. As; what C. That; what D. What; that
6. I don’t say I am against Jackie’s plan. But the problem is ___________he does
from the serious disease soon.
A. what that B. that what C. whether what D. what whether
7. “ When ________ leave for Japan?” “When _______ leave for Japan is kept
secret.”
A. they will; will they B. will they; they will
C. they will; they will D. will they; will they
8. They lost their way in the forest, and _________ made matters worse was that night
began to fall.
A. it B. which C. that D. what
9. It has come to my notice ________ some of you have missed to do anything well.
A. what B. which C. that D. when
10. _______ we are doing has never been done before.
A. That B. What C. Which D. Whether
2）家庭作业：
1. _____ as much as one-fifth of all timber harvested is not used.
A. The estimate B. The estimated
C. They are estimated D. It is estimated that
2. _____ some mammals came to live in the sea is not known.
A. Which B. Since C. Although D. How
3. _____ we have achieved is attributed to the guidance of our parents.
A. Whoever B. Whatever C. However D. That
4. _____ wealthy does not necessarily mean that a man is greedy.
A. For the reason that he is B. Just because he is
C. The reason of being D. That he is
5. Although ___ happened in this developed country sounds like science fiction, it c
ould occur
elsewhere in the world.
A. which B. what C. how D. it
6. _____ she had forgotten to take her notebook.
A. That occurred to her B. She occurred that
C. To her that occurred D. It occurred to her that
7. I am sure that _____ she said is wrong.
A. which B. all C. this D. what
8. We lost our way in the forest, and ____ made matters worse was that it was getting
dark.
A. that B. which C. it D. what
9. _____ or not is still uncertain.
A. He’s coming B. If he is coming
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C. That coming D. Whether he’s coming
10. It’s _____ he’ll be able to come.
A. doubt whether B. doubtful C. doubt it D. doubtful whether
11. ______ he is at work in the heart of the big city or at home in the quiet suburb, Di
ck’s life is tied to machines.
A. Whether B. Till C. If D. Unless
12. _____ he saw both surprised and frightened him.
A. That B. When C. What D. Which
13. _____ is warm sunshine.
A. What do we all need. B. What all we need
C. What we need D. What we all need
14. _____ is a pity that he should feel so upset.
A. What B. That C. He D. It
15. _____ a spoonful of soil can tell us so much about the structure and early history o
f the moon.
A. Remarkable B. Quite remarkably
C. It is remarkable that D. It is remarkable fact that
16. _____ you nominate will be elected.
A. Who B. Whom C. Whomever D. That’s
17. _____ book you borrow must be returned within a week.
A. What B. Which C. Whichever D. That’s
18. _____ of us gets home first starts cooking.
A. Who B. Which C. Whichever D. Anyone
19. It’s known to us all ___ a form of energy .
A. water is B. that water is
C. is water D. that water to
20. It worried her a bit ___ her hair was turning gray.
A. whether B. that C. what D. when
I say and think ___ none of your business.
A. is B. are C. has D have
22.___ is known to us all that America is a developed country .
A Which B As C What D It
23. ___we’ll go camping tomorrow depends on the weather .
A If B Whether C That D Where
24.___ he made an important speech at the meeting was true.
A. That B. Why C. What D. How








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答案：
1）1-5 ADCBC 6-10 BBDCB
2)
19-24 BBADBA
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