一、主语从句的概念与类型
主语从句在复合句中作主句的主语,引导主语从句的词有从属连词that, whether以及连接代词who, what, which, whoever, whatever, whichever和连接副词when, where, why, how等.例如:
That she was chosen made us very happy.她当选了使我们很高兴.
What caused the accident is a complete mystery.是什么导致了这次事故还完全是一个谜.
Whether she will come or not is still a question.她是否来还是一个问题.
Which team will win the match is still unknown.哪个队会赢得这场比赛还不知道.
Whoever comes to the party will receive a present.参加聚会的每一个人都将收到一份礼物.
When they will start has not been decided yet.他们何时出发还没决定.
注意:上述例句中的主语从句都是放在句首,但有时为了使句子结构平衡,避免"头重脚轻",常用it作形式主语,而把从句放在后面.例如:
It is a pity that she has made such a mistake.她犯了这样一个错误,真是遗憾.
It depends on the climate whether they are going shopping today.他们是否今天去购物还得看天气情况.
这样就构成了下面一些常用句型:
1)It is + adj. / n. +从句
It is a pity/shame that...遗憾的是……
It is possible that...很可能……
It is unlikely that...不可能……
2)It +不及物动词+从句
It seems/appears that...似乎……
It happened that...碰巧……
3)It + be +过去分词+从句
It is said that...据说……
It is known to all that...众所周知……
It is reported that...据报道……
It is believed that...据信……;人们相信……
It is suggested that...有人建议……
It must be pointed out that...必须指出……
It has been proved that...已证明…….例如:
It is believed that at least a score of buildings were damaged or destroyed.据信,至少有二十座楼房遭到破坏或彻底毁掉.
It is suggested that the meeting should be put off.有人建议会议延期召开.
It's reported that three people were killed in the accident and five were hurt badly.据报道,事故中三人丧生,五人重伤.
It is known to all that Taiwan is an inseparable part of China.众所周知,台湾是中国不可分割的一部分.
[巩固练习]
1. Does _______ matter if he can't finish the job on time?
A. this
B. that
C. he
D. it
2. It worried her a bit _______ her hair was turning grey.
A. which
B. that
C. if
D. for
3. _______ is a fact that English is being accepted as an international language.
A. There
B. This
C. That
D. It
二、学习主语从句应该注意的几个问题
1)引导词that与what
what既有引导主语从句的作用,同时又在从句中作句子成分(主语、宾语、表语等).这时what相当于all that/everything that...,常译成"所……的(东西、事情、话等.)";而that只起连接作用,本身无实际意义,在从句中也不担当任何句子成分.但that引导的主语从句放在句首时,不能省略that.例如:
What is done can't be undone. (谚语)已成定局,无可挽回.
What we can't get seems better than what we have.我们得不到的东西似乎比已得到的要好.
That we should work out a plan to deal with the present serious situation is important.我们应该制定一项计划来应付目前严峻的形势,这一点非常重要.
That a new teacher will come to teach us geography is true.一位新老师将来教我们地理,这是真的.
[巩固练习]
4. _______ what they told me really true?
A. Has
B. Is
C. Does
D. Have
5. It matters little _______ a man dies, but _______ matters much is _______ he li ves.
A. how; what; how
B. how; it; how
C. why; it; why
D. that; what; that
6. _______ she couldn't understand was _______ fewer and fewer students showed interest in her lessons.
A. What; why
B. That; what
C. What; because
D. Why; that
7. It is pretty well understood _______ controls the flow of carbon dioxide in and out the atmosphere today.
A. that
B. when
C. what
D. how
8. _______ fashion differs from country to country may reflect the cultural differences from one aspect.
A. What
B. That
C. This
D. Which
9. -What made her parents so angry?
- _______ she had failed in the examination.
A. As
B. Because
C. Since
D. That
2)引导词if和whether
if和whether引导动词后的宾语从句时一般可通用,但介词后的宾语从句、主语从句(放在句首时)、表语从句常由whether引导.例如:
Whether she will go home or not is unknown.她是否回家还不得而知.
Whether we shall raise ducks or geese remains to be decided.我们是养鸭还是养鹅仍没决定.
=It remains to be decided whether/if we shall raise ducks or geese.
但我们不能说If we shall raise ducks or geese remains to be decided.
[巩固练习]
10. _______ we'll go camping tomorrow depends on the weather.
A. If
B. Whether
C. That
D. Where
3)其它引导词
连接代词who, which, whom, whose有各自的意义,起连接作用,并在从句中充当语、宾语、表语、定语等;连接副词when,where, why, how等有各自的意义,起连接作用,并在从句中充当状语.
[巩固练习]
11. -Do you remember _______ he came?
-Yes, I do. He came by car.
A. how
B. when
C. that
D. if
12. It was a matter of _______ would take the position.
A. who
B. whose
C. whom
D. whomever
13. -I drove to Zhuhai for the air show last week.
-Is that _______ you had a few days off?
A. why
B. when
C. what
D. where
14. I read about it in some book or other, does it matter _______ it was?
A. where
B. what
C. how
D. which
三、语气
在It is necessary / natural / important / strange...+ that-clause这类句型里,that所引导的主语从句中谓语动词用"should +原形",表虚似语气.例如:
It is necessary that the problem should be settled at once.这个问题必须马上解决.
It's strange that he should have gone away without telling us.他竟然没向我们说一声就走了,真是奇怪.
[巩固练习]
15. It is necessary that a college student _______ at least a foreign language.
A. masters
B. should master
C. mastered
D. will master
四、以it作形式主语的主语从句与强调句型的区别
"It be + adj./n. + that-clause"与强调句型均有It be...that...之类的语言标志,但不同的是:①前者中的that 从句是主语从句.若删掉其中的It be和that,则剩余部分不论结构还是语意都不能成为一个句子;但若将后者中的It be和that去掉,则剩余部分的结构和语意仍能构成一个完整的句子.②强调句型译为汉语时可加上"正是……"或"就是……"之类的字眼,而主语从句则不可以.请比较下面两个句子:
It is surprising that Mary should have won first place.令人惊奇的是玛莉竟然获得了第一名.
It is Mary that has won first place.正是玛莉得了第一名.
第一句话中的It是形式主语,that引导的是主语从句.句中的It is和that无法删除,一旦删除句子就不成立.
第二句是强调句型,其中的It is和that可以去掉,因为没有It is和that句子仍然很通顺.
Key: 1-5 DBDBA 6-10 ACBDB 11-15 AAADB
名词性从句---主语从句 1. What is needed for the space trip is careful preparation. 2. Her wish is that she can lose weight soon. 3. I think that woman can reach every high achievements in many fields of science. 4. We were very excited at the news that our team had won. 引导名词性从句的关联词可分为三类： 一．从属连词：that（无任何词意） whether, if（均表示“是否”表明从句内容的不确定性） as if ,as though（均表示“好像”，“似乎”）以上在从句中均不充当任何成分二．连接代词：what, who, whom, which，whose, whatever, whoever, whichever(作主宾表定) 三．连接副词：when, where, how, why(作状语) I.主语从句 1.定义：在句子中担当主语的是一个从句,这个从句就叫做主语从句。 2.位置：主语从句是在复合句中充当主语的从句，通常放在主句谓语动词之前或由形式主语it 代替，而本身放在句子末尾。 3.引导主语从句的关联词： (1)从属连词that,whether,if (在从句中不充当成分，仅起连接作用) That Jack won the match yesterday surprised us. Whether he’ll come here isn’t clear. (此处不能用if) (2)连接代词who, whom, whose, what, which, whoever, whatever, whichever(充当主宾表定) What she did is not known. Whoever comes is welcome. (3)连接副词where,when,how,why(在从句中充当状语) How this happened is not clear to anyone. When the meeting will be held is decided by our manager. 4.有时为了避免头重脚轻，常用it作形式主语，而把真正主语放在句子末尾。 How the book will sell depends on its author. = It depends on its author how the book will sell. That he is the best student in the class is obvious. = It is obvious that he is the best student in the class. 用it作形式主语的几种常见结构： (1) It is ＋名词＋从句 It is a fact that … 事实是… It is an honor that …非常荣幸 It is common knowledge that …是常识 (2) It is ＋形容词＋从句 It is natural that… 很自然It is strange that… 奇怪的是… (3) It is ＋不及物动词＋从句 It seems that… 似乎… It happened that… 碰巧… It ap pears that… 似乎… (4) It ＋过去分词＋从句
高考英语主语从句 定义：用作主语的从句叫主语从句，它是名词性从句之一。主语从句的时态：不受主句的时态影响和限制。引导主语从句的连接词有： 从属连词: that, whether； 连接代词: who (whoever), whom, whose, what (whatever)和which (whichever)； 连接副词: when, where, how和why。 连接词： 1. 从属连词：that，whether 1）that引导主语从句只起引导作用，在主语从句中不充当任何成分，that本身无实际意义，但不能省略。2）whether意为“是否”，放在句首句末皆可。由whether引导的名词从句做主语，表语，介词宾语，同位语时！不可用if代替。 a.That price will go up is certain. b. Whether they would support us was a problem. 他们是否会支持我们还是一个问题。 2. 连接代词who ，what ，which, whatever, whichever, whoever (Who, whom, which, what可以和ever构成合成词，和what一样引导从句，ever起到强调作用。此类主语从句不能用形式主语it引导，它们在句子中担任成分，不能省略，语序为陈述语序，既有疑问含义,又起连接作用,同时在从句中充当各种成分。 Which side will win is not clear. Whoever breaks the law will be punished. Whatever he did is right. Who killed the scientist remains a question. 1）What和that引导的主语从句的区别：that 只起引导作用，不充当任何成分，没有意思。What 不仅起引导作用，还要充当一定成分(主语、宾语或表语)，意思是：“什么”。 What we need is money. That he will come is certain. 2）whatever / whoever的用法（~ever=no matter ~---让步状语从句中） whatever / whoever可以引导主语从句,并在句中作主语、宾语、表语等,不含疑问意义。whatever相当于anything that; whoever 相当于anyone who。例如: Whoever(Anyone who) wants to enter into this school must take the exam. Whatever(Anything that) she did was right. 3. 连接副词when，where，how，why等。既有疑问含义,又起连接作用,同时在从句中充当各种成分。How this happened is not clear to anyone. When he will be back depends on the weather. When we’ll start tomorrow will be told soon. Where the test will be given is not yet decided. 4. 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. 例: That we shall be late is certain. -- It’s certain that we shall be late. 1）用it 作形式主语的结构 A. It + be + 形容词+ that 从句 (obvious, true, surprising, good, wonderful, funny, possible, likely, certain, probable, etc.) 如：It is certain that she will do well in her exam. B. It + be + 名词词组+ that 从句(an honour, a fact, a pity, etc）如： It is a pity/shame that... 遗憾的是…… It is a surprise that…令人惊奇的是… It is a fact that… …是事实It is common knowledge that… …是常识 It’s a pity that we can’t go. C. It + be + 过去分词+ that 从句(said, reported, thought, expected, decided, announced, etc。）如：It is said that Mr. Green has arrived in Beijing. D. It + 不及物动词或短语+ that 从句( seem，happen, doesn’t matter ,turn out）。如： It happened that I was out that day. It doesn’t matter whether she will come or not. 2) 对于以连接代词(副词)引导的主语从句,可以使用形式主语代主语从句,也可直接在句首使用主语从
高中英语语法主语从句 第一节主语从句 1．考点解析。 1．主语从句一般分为三类：由what等代词引导的主语从句；由连词that 引导主语从句，多数情况下由it作形式主语，that从句放到句子后面去；由连接代词或连接副词（或whether）引导的主语从句。 What they are after is beauty. It is not your fault that we can’t arrive on time. When they will arrive has not been decided. 2. 由关系代词what引导的主语从句，也可由whatever（“所…的一切”）或 whoever（“一切…的人”）引导。 Whatever he wants is your support. Whoever comes will be welcome. 3. 大多数主语从句都可用it代替，作形式主语，把主语从句放在句尾。要注意it代替主语从句和it引导的强调句的区别。强调句的结构是it is/was….+that…，强调人是可把that 换做who，whom，whose。如强调的是状语时，也只能用that,而不能用when, where, how, why等。 It was in Paris that they fell in love with each other. It is the lady who was my English teacher. It was last semester that he won the first prize. 2. 试题详解。 1．______ he needs is more experience. A. Who B. That C. What D. How 2.It was because of the heavy snow ______ the train was late. A. why B. that C. so D. thus 3．It doesn’t matter ______ he likes or not. A. whether B. what C. when D. that 4______ he has won the Noble Prize has been proved to be true. A. What B. How C. It D. That 5．What he wants _______ to sleep more. A. are B. have been C. is D. were 6．______ we can begin this investigation is still a question. A. When B. Why C. What D. That 7．It is ______ that the highway will be open to traffic nest year. A. report B. reported C. reporting D. by report 8．______ fails to see this will make a big mistake. A. Whatever B. what C. wherever D. Whoever 9．It is a mystery _____ the prisoner escaped. A. why B. how C. what D. that 10．It was last summer _____ he graduated from the college. A. that B. when C. / D. where 3. 实战演练。 1. We didn’t know ______ she didn’t come. A. why B. that C. when D. it 2. It is still doubtful _______ she would play the part.
练习（主语从句） 一、.关联词分类和基本句型： (1)从属连词that。如：That they were indeed sisters was clear from the facial resemblance between them. 很明显，她们确是亲姐妹，她们的脸型很相似。 ______ we need more equipment _____ quite obvious. 我们需要更多的设备，这是很明显的。 (2)从属连词whether。如： Whether he’ll come here isn’t clear.他是否会来这里还不清楚。 ______ he will join us won't _____ too much difference.他是否和我们一起干无所谓。 (3)连接代词who, whom, whose, what, which, whoever, whatever, whichever 连接副词where, when, how, why。如： What you need is more practice. 你需要的是更多的练习。 Whoever wants it may have it. 谁要都可以给他。 _____she did ____ not yet known. 她干了什么尚不清楚。 _____ this happened is not _____ to anyone. 这事怎样发生的，谁也不清楚。 ______ comes _____ welcome. 不论谁来都欢迎。 二、主语从句后置： 主语从句能用it作形式上的主语。常以it作形式主语的句型有： A.It+be+形容词(obvious, true, natural, surprising, good, wonderful, funny, possible, likely, certain, probable, etc.)+that从句。如： It is certain that she will do well in her exam. 毫无疑问她考试成绩会很好。 _____ _____ probable ______ he told her everything. 很可能他把一切都告诉她了。 B.It+be+名词词组(no wonder, an honour, a good thing, a pity, no surprise, etc.)+that从句。如：It’s _____ ______ that we can’t go.很遗憾我们不能去。 It’s ______ _______ that our team should have won the game. 我们没赢这场比赛真意外。 C.It+be+过去分词(said, reported, thought, expected, decided, announced, arranged, etc.)+that从句。如： It is ______ ______Mr. Green has arrived in Beijing. 据说格林先生已经到了北京。 It is ______ _______ China has sent another man-made earth satellite into orbit. 据报道中国又成功地发射了一颗人造地球卫星。 D.It+seem, happen等不及物动词及短语+that从句。如： It seems that Alice is not coming to the party at all. Alice似乎不来参加晚会。 _____ _______ ______ I was out that day. 碰巧我那天外出了。 E.It+doesn’t matter (makes no difference, etc.)+连接代词或连接副词引起的主语从句。如： It doesn’t ______ _______ she will come or not. 她是否来这无关紧要。 It _____ _____ difference ______ we shall have the meeting. 我们在哪里开会毫无区别。 三、注意连接代词whoever, whatever, whichever等引导主语从句的含义： _______ comes will be welcome. (whoever=the person who) 来的都是客。 _________ he did was right. (whatever=the thing that) 他所做的事情都是正确的。 ________ _____ ______ comes in will receive a prize. (whichever=anyone of you who) 你们当
语法要点剖析 一、名词性从句 主语从句、表语从句、宾语从句、同位语从句，在整个句子中所起的作用，相当于一个名词。因此，这四种从句通称为名词性从句。 引导名词性从句的连接词可分为三类： 连接词：that, whether, if （不充当从句的任何成分） 连接代词：what, whatever, who, whoever, whom, whose, which. 连接副词：when, where, how, why 1. 主语从句 作句子主语的从句叫主语从句。主语从句通常由从属连词that，whether，if 和连接代词what，who，which，whatever，whoever以及连接副词how，when，where，why等词引导。that在句中无词义，只起连接作用；连接代词和连接副 词在句中既保留自己的疑问含义、又起连接作用，在从句中充当从句的成分。例如： What he wants to tell us is not clear. 他要跟我们说什么，还不清楚。 It is known to us how he became a writer. 我们都知道他是如何成为一名 作家的。 Where the English evening will be held has not yet been announced. 英语晚会将在哪里举行，还没有宣布。 有时为避免句子头重脚轻，常用形式主语it代替主语从句作形式主语放于句首，而把主语从句置于句末。主语从句后的谓语动词一般用单数形式。常用句型如下： （1）It + be + 名词+ that从句（2）It + be + 形容词+ that从句 （3）It + be + 动词的过去分词+ that从句（4）It + 不及物动词+ that 从句 另注意在主语从句中用来表示惊奇、不相信、惋惜、理应如此等语气时，谓语动词要用虚拟语气“(should) +do”，常用的句型有： It is necessary (important, natural, strange, etc.) that … It is a pity (a shame, no wonder, etc.) that… It is suggested (requested, proposed, desired, etc.) that… 2. 宾语从句 名词句用作宾语的从句叫宾语从句。引导宾语从句的关联词与引导主语从句表语从句的关联词大致一样，在句中可以作谓语动词或介词及非谓语动词的宾语。 1. 由连接词that引导的宾语从句 由连接词that引导宾语从句时，that在句中不担任任何成分，在口语或非正式的文体中常被省去，但如从句是并列句时,第二个分句前的that不可省。例如：He has told me that he will go to Shanghai tomorrow.他已经告诉我他明天要去 上海。 We must never think (that) we are good in everything while others are good in nothing. 我们决不能认为自己什么都好，别人什么都不好。
高中英语主语从句知识点整理 课 件www.5y https://www.doczj.com/doc/6c507531.html, 1.定义：用作主语的从句叫做主语从句。 2.构成：关联词+简单句 3.引导主语从句的关联词有三类： 从属连词that。 例如：Thattheywereintruthsisterswasclearfromthefacialrese mblancebetweenthem.很明显，她们确是亲姐妹，她们的脸型很相似。 从属连词whether。 例如：whetherhe'llcomehereisn'tclear.他是否会来这里还不清楚。 连接代词： who whom whose what which whoever whatever
whichever 连接副词： where when how why 例如： whatshedidisnotyetknown.她干了什么尚不清楚。 Howthishappenedisnotcleartoanyone.这事怎样发生的，谁也不清楚。 whoevercomesiswelcome.不论谁来都欢迎。 whereveryouareismyhome----myonlyhome.你所在的任何地方就是我的家----我唯一的家。 注：主语从句能用it作形式上的主语。常以it作形式主语的句型有： A. It+be+形容词+that从句。 例如： Itiscertainthatshewilldowellinherexam.毫无疑问她考试成绩会很好。 Itisprobablethathetoldhereverything.很可能他把一切都告诉她了。
B. It+be+名词词组+that从句。 例如： It'sapitythatwecan'tgo.很遗憾我们不能去。 It'snosurprisethatourteamshouldhavewonthegame.我们没赢这场比赛真意外。 c.It+be+过去分词+that从句。 例如： Itissaidthatmr.GreenhasarrivedinBeijing.据说格林先生已经到了北京。 Itisreportedthatchinahassentanotherman-madeearthsat elliteintoorbit.据报道中国又成功地发射了一颗人造地球卫星。 D.It+seem,happen等不及物动词及短语+that从句。 例如： ItseemsthatAliceisnotcomingtothepartyatall.Alice似乎不来参加晚会。 IthappenedthatIwasoutthatday.碰巧我那天外出了。 E.It+doesn'tmatter+连接代词或连接副词引起的主语从句。
xx考研英语语法复习主语从句 在复合句中充当主语成分的句子叫作主语从句。具体形式为：引导词引导一个从句作主语;或者it作形式主语+谓语/系表结构+引导词+从句。 ⑴陈述句充当主语从句，连词为that(that没有实际含义，在从句中只起连接作用，不在从句中作任何语法成分)，从句为"that+陈述句"，that不能省略。 【例句】 That Chris Lee won the champion of Super Girl in xx arouse wide public concern. 李宇春赢得xx年超女冠军这件事引起了社会的广泛关注。 ⑵一般疑问句充当主语从句，连词为whether(whether"是否"的含义，在从句中只起连接作用，不在从句中作任何语法成分)，从句为"whether+陈述句语序"，whether不能省略。 【例句】 Whether this is true or not remains a mystery. 这是对是错还是个谜。 ⑶特殊疑问句充当主语从句，连词为特殊疑问词(特殊疑问词都有自己的含义，在从句中作一定的语法成分)，从句为"特殊疑问词+陈述句语序"，特殊疑问词不能省略。 【例句】 例1 --what
What caused the aident remains unknown. 是什么引起了这一事故仍然。 例2--where Where my wife and I should enjoy our honeymoon is still unsettled. 我太太和我应该去哪享受我们的蜜月还没有最后决定。 例3 --which Which university I should choose to continue my further education is a question of great importance. 我应该考哪个大学的研究生是个很重要的问题。 例4--when When and where the test will be given is not yet decided. 什么时候在什么地方进行考试还没定下来。 例5---ever Whoever gets the job will have a lot of work to do. 任何得到这份工作的人都将要有很多工作要做。 例6--how How we can protect the grain from damp needs to be discussed. 我们怎样才能保护粮食不受潮需要讨论讨论。 3.It句型
要考试，找戴氏戴氏教育乐山分校主讲教师：徐海燕 主语从句——突破高考 1、名词性从句的概念：名词性从句相当于名词。 主语从句 2、名词性从句种类表语从句 宾语从句 3、引导名词性从句的关系词：①从属连词：that；whether；if；as if（表语从句） ②连接代词：who；whom；whose；what；which ③连接副词：when；where；why；how 以及how组成 的短语：how many；how long；how far。。。 （1）主语从句 Eg：A、What surprised me most was to see some of the village people seated on the benches at the end of room. B、That he will come is certain. C、Whether she’s coming or not doesn’t matter too much. D、Which team will win the match is a matter of public concern. E、Where she has gone is not known yet’ ※主语从句较长时，放句末，用it 作形式主语。 Eg：It was well known that Napoleon always asked the same three questions，and usually in the same order. It is uncertain whether he can come or not. It remains a secret how they climbed up the mountain. It has not been decided when they will leave for New York. 总结：用it作形式主语有以下几种常用句型： ①it + be + 形容词+从句 ②it + be + 名词词组+从句 ③it + be + 过去分词+从句 ④it + seems ; happen ;等不及物动词+从句 直击高考： 1、______leaves the room last ought to turn off the light. A、Anyone B、The person C、Whoever D、Who 2、______the Olympic Games will be held in Beijing is not known yet. A、Whenever B、If C、Whether D、That 3、_____he said at the meeting astonished every present. A、What B、That C、The fact D、That 4、_____we can’t get seems better than ______ we have. A、What ; what B、What ;that C、That ; that D、That ;that 5、_____ troubles me is ______ I can’t learn all these English idioms by heart. A、That ; that B、What ; that C、That ; what D、What ;\ 6、______fashion differs from country to country may reflect the cultural differences from one aspect. A、What B、That C、This D、Which
名词性从句之主语从句 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： 1.It+ 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.
主语从句详解 一、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、主语从句主要有四类 （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. That you are so indifferent bothers me. That she survived the accident is a miracle. （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. 例如：Whether we will hold a party in the open air tomorrow depends on the weather. Whether she is coming or not doesn’t matt er 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. 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when, where, why, how引导名词性从句(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. 三、注意点: it构成的主语从句 （1）由连词that引导的主语从句, 在多数情况下放到句子的后面, 而用代词it作形式主语. 例如：That light travels in straight lines is known to all. =It is known to all that light travels in straight lines.
主语从句 （一）主语从句的标记主语从句通常由连词that和whether (if)、连接代词或连接副词以及关系代词型what引导。 1. that引导 That he is still alive is a wonder. 他还活着，真是奇迹。 That we shall be late is certain. 我们要晚了，这是确定无疑的。 That he should have ignored the working class was natural. 他忽视工人阶级是很自然的。That she is still alive is a consolation. 她还活着是使人感到宽慰的。 That she became an artist may have been due to her father’s influence. 她成为画家可能是受她父亲的影响。 That you are coming to London is the best news I have heard this long time. 你将来伦敦是好久以来我听到的最好消息。 That she was chosen made a tremendous stir in her village. 她被挑选上，在她村子里引起很大轰动。 2. whether引导 Whether it will do us harm remains to be seen. 是否对我们有害还要看一看。 Whether they would support us was a problem. 他们是否会支持我们还是一个问题。 3. 连接代词引导 Whoever (=anyone who) fails to see this will make a big blunder. Whatever(=anything that) she did was reasonable. 无论什么 Anything that she did was reasonable. Whichever (of you) comes in first will receive a prize. 无论(你们)谁先到都可以得奖。Whichever(=anything that) you want is yours. 你要哪个哪个就是你的。 What do you need? What you need is a good rest. I don’t know what you need? 4. 连接副词引导 When we arrive doesn’t matter. 什么时候到没有关系。 When do we arrive? How it was done was a mystery. 这是怎样做的是一个谜。 How was it done? How this happened is not clear to anyone. 这件事怎样发生的，谁也不清楚。 How did this happen? How many people we are to invite is still a question. 邀请多少人还是一个问题。How many people are we to invite? Where I spend my summer is no business of yours. 我在哪里过暑假不关你的事。 Where do i spend my summer? 5. 连接代词型what引导 What(=the thing that) we need is money. 我们需要的是钱。What do we need? What I want to know is this. 我想知道的就是这一点。What’s done is done. 事已成定局。 What=the thing that he says is not important. 他说的话并不重要。What does he say? What I am telling you is mere impressions. 我和你说的都不过是一些印象而已。What make the river more beautiful are the lotus plants growing in the water. 为河水增色的是水里的荷花。What you need is a good-sized canvas bag. 你需要的是一个比较大的帆布袋。 What I am afraid of is their taking him to Portugal. 我担心的是他们把他带到葡萄牙去。What struck me was that they have all suffered a lot. 给我很深印象的是他们都受过很多苦。（二）
主语从句 在从句中充当主语的复合句，主语即为主句动作的发出者或状态的持有者。有两种形式：直接放句首；it 为形式主语，真正的主语在句子后（为了避免头重脚轻）。主语从句时态不受主句的限制。 （一）连接词引导的主语从句 主语从句在复合句中作主句的主语,引导主语从句的词有从属连词that, whether以及连接代词who, what, which, whoever, whatever, whichever和连接副词when, where, why, how等. 连接词引导的从句 That light travels in straight line is known to all.我们都知道光是以直线传播的。 Whether he will join us is still a question.他是否会加入我们仍是个问题。 连接代词引导的从句 Who will be sent there has not been decided.大家还没有决定谁会被送过来。（主语） What you need is more practice. 你需要更多的练习。(宾语) Whatever we do is to serve the people.我们无论做什么都是为了服务人民。（宾语） Which is the best is not clear.我们不清楚哪个最好。(主语) 连接副词引导的从句 Where he has gone is a question.我们不知道他去哪儿了。（地点状） How he can earn a living in London remains a big problem. 如何在伦敦谋生仍是个大问题。（方式状） When we shall have our sports meet is a mystery. 什么时候会开运动会仍是个迷。（时间状） 注意：在主语从句中，为了避免头重脚轻的问题，常用it为形式主语，真正的主语在句子后。（上述的例子转换） （二）总结it为形式主语的结构： 1)It is + adj. / n. +从句 It is a pity/shame that...遗憾的是…… It is possible that...很可能……