主语从句和同位语

1、主语从句一、主语从句的连词分三类（1）从属连词引导的主语从句（that whether if ）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。That引导主语从句通常用it作形式主语。例如： That you will win the medal seems unlikely.That she survived the accident is a miracle.whether 引导的主语从句 : whether 有含义 （是否）/在句中不做成 分/不可以省略。注意：引导主语从句，不能用 if 不能在开头，只能用 whether。Whether we will ho

2、ld a party in the open air tomorrow depends on the weather.Whether she is coming or not doesn 'mtatter too much.（2）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.Whatever we do is

3、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 puni shed.)Whoever breaks

4、 the law, he should be punished. (让步状语从 句)( =No matter who breaks the law, he should be puni shed.)( 3)用连接副词 when, where, why, how 引导的名词性从句 (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 'bteen made pubic.三、 it 作形式主语的主语从句有时为了考虑句子平衡，通常在主语从句处使用形式主语it，而将真正的主

5、语从句移至句末。这分四种情况：(1) 对于以连词 that 引导的主语从句，通常用形式主语 it 替代主 语从句：<a> It is +名词 +从句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 com mon knowledgethat 是常识 类似的名词还有： a pity； a wonder； a good thing； no wonder； surprise 等。It is a mystery to me how it all happened.It is co

6、mmon knowledge that the whale is not a fish.It is no surprise that Bob should have won the game.<b> It is + 形容词 +从句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

7、; unusual; certain; evident; worth-while; surprising; interesting; astonishing, etc.It is doubtful whether she will be able to come.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.需要注意的是这类主语从

8、句中，谓语动词很多为“（should） +动词原形”，即要用虚拟语气。<c> It is +过去分词 +从句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; fou

9、nd out,etc.例如： It is used to be thought that a new star must be due to a collision between two stars.It has not been made clear when the new road is to be opened to traffic.<d> It seems 不及物动词( happened / appears /doesn 'tt matter / makes no differenee / occurred )that 主语从句不可提前It makes no d

10、ifference 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) 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句：Whether they would support us was a problem. 他们是否会支持我 们还是一个问题。It was a problem whether they would support us. 他们是否会支

11、持我 们还是一个问题。(3) 对关系代词型 what 引导的主语从句， 通常直接将主语从句放 在句首。如：What we need is money. 我们需要的是钱。What I want to know is this. 我想知道的就是这一点。 有时也可将助用形式主语。如： It is clear enough what he meant. 他是什么意思很清楚。(4) 如果句子是疑问句，则必须用带形式主语 it 的结构：Is it true that he is the girl 's father? 他是那女孩的父亲，是真的 吗？How is it that you are la

12、te again? 你怎么又迟到了？四、连词 that 的省略问题 引导主语从句的连词 that 有时可省，有时不能省，其原则是： 若 that 引导的主语从句直接位于句首，则 that 不能省略；若 that 引导的主语从句位于句末，而在句首使用了形式主语it ，则 that可以省略：That you didn 't go to the talk was a pity. 很遗憾你没去听报告。 (that 不可省 )It was a pity (that) you didn 't go to the talk. 很遗憾你没去听报告。 (that 可省 )同位语从句一、理解同位语

13、从句的含义，把握同位语从句的实质在主从复合句中作同位语的从句称为同位语从句。 同位语从 句一般用 that, whether， what, which, who, when, where, why, how 等词引 导，常 放在 fact, news, idea, truth, hope, problem, information, wish,promise, answer, evidence, report, explanation, suggestion, conclusion 等抽象名词后面，说明该名词的具体容。 换言之， 同位语从句和所修饰的名词在容上为同一关系， 对其容 作进一步说明

14、。例： The news that they had won the game soon spread over the whole school.他们比赛获胜的消息很快传遍了整个学校。析：they had won the game说明The news的全部容，因此该句为 同位语从句。二、正确运用同位语从句的引导词，准确把握同位语从句1. 如同位语从句意义完整，应用that 引导同位语从句。 （即 that不充当任何成分，只起连接作用，不可省略）例： The general gave the order that the soldiers should cross theriver at o

15、nee.将军下达了战士们立即过河的命令。析: the soldiers should cross the river at once是 the order 的全部容，且意义完整，因此应用that引导同位语从句。2. 如同位语从句意义不完整， 需增加 "是否 "的含义， 应用 whether 引导同位语从句。 （if 不能引导同位语从句）例： We'll discuss the problem whether the sports meeting will be held on time.我们将讨论运动会是否会如期举行的问题。析：the sports meeting

16、will be held on time 意义不完整，应力口 "是否 "的含义才能表达 the problem 的全部容，因此应用 whether 引导同位语从句。3. 如同位语从句意义不完整，需增加 "什么时候 "、"什么地点 "、" 什么方式 "等含义，应用 when, where, how 等词引导同位语从句。例 1： I have no idea when he will be back.析： he will be back 意义不完整， 应加 "什么时候 "的含义才能 表达 idea

17、的全部容，因此应用 when 引导同位语从句。例 2： I have no impression how he went home, perhaps by bike. 析： he went home 意义不完整，应加 "如何 "的含义才能表达 impression 的全部容，因此应用 how 引导同位语从句。4. 当主句的谓语较短， 而同位语从句较长时， 同位语从句常后置。 如： The thought came to him that maybe the enemy had fled the city.三、把握同位语从句和定语从句的区别， 明确同位语从句和相似 从句的界限

18、同位语从句和定语从句相似， 都放在某一名词或代词后面， 但同位语从句不同于定语从句。 同位语从句对名词加以补充说明， 是 名词全部容的体现， 且名词和同位语从句的引导词均不在从句中 作成分； 定语从句说明先行词的性质与特征， 与先行词是修饰与 被修饰的关系，且名词和定语从句的引导词均在从句中作成分。 区分时可以在先行词与与从句之间加一个系动词be,使之构成一个新句子，如果句子通顺且符合逻辑，则为同位语从句，反之， 则为定语从句。如： The report that he was going to resign was false.因为 the report was that he was go

19、ing to resign 句意通顺，所以， that he was going to resign 是同位语从句。例 1：1) Information has been put forward more middle schoolgraduates will be admitted into universities.A. while B. that C. when D. as析： 答案为 B。more middle school graduates will be admitted into universities 是 Information 的容，且 Information 不在从句中

20、 作成分，所以该句为同位语从句。应将该句区别于：2) It is said that more middle school graduates will be admitted intouniversities， this is the information has been put forward.A. what B. that C. when D. as析：答案为 B。that has been put forward 为 information 的修 饰性定语，且 information 在从句中作主语，所以该句为定语从 句。例 2： She heard a terrible nois

21、e, brought her heart into hermouth.A. it B. which C. this D. that析：答案为B。分析语境含义、句子结构和句子成分可知， 该句为非限制性定语从句，先行词为a terrible noise，且它在从句中作主语。应将该句区别于：I can't stand the terrible noise she is crying loudly.A. it B. which C. this D. that析：答案为 D。 she is crying loudly 是 the terrible noise 的容， 且 the terrible

22、 noise 不在从句中作成分，所以该句为同位语从句。同位语从句和定语从句的三点区别同位语从句和定语从句很相似,但还是有区别的 ,区别主要在以下三方面 :1. 从词类上区别 同位语从句前面的名词只能是 idea,fact,news,hope,belief,suggestion,proposal,word,thought,doubt,tr uth,possibility,promise,order 等有一定涵的名词 ?而定语从句的先 行词可以是名词 ?代词 ?主句的一部分或是整个主句 ?女口:The possibility that the majority of the labour forc

23、e will work at home is often discussed. （同位语从句 ）We are not looking into the question whether he is worth trusting. （同位语从句 ）Word came that he had been abroad.同位语从句 ）Our team has won the game, which made us very happy. 我们的队赢了 ,这让我们很高兴 ?（定语从句 ）The doctor whom you are looking for is in the room. 你找的那位医生

24、在房间里面 ?（定语从句 ）His mother did all she could to help him with his study. 他妈妈尽她 的最大努力帮助他的学习 ?（定语从句 ,代词 all 作先行词 ?）2. 从性质上区别定语从句是从句对其先行词的修饰或限制,属于形容词性从句的畴;而同位语从句是从句对前面抽象名词的进一步的说明和解释,属于名词性从句的畴。如 :The news that our team has won the game was true. 我们队赢了那 场比赛的消息是真的 ?（同位语从句 ,补充说明 news 到底是一个什 么消息 ）The news that he told me yesterday was true. 昨天他告诉我的那个 消息是真的？（定语从句，news在从句中作told的宾语）I made a promise that if anyone set me free I would make him very rich. 我许诺如果谁让我自由 ,我就让他非常富有 ？（同位语从句 ,补 充说