1、（1）定语从句中做主语（2）由that引导主语从句放句首时（3）that引导同位语从句时（4）宾语从句中i it做形式宾语，真正的that宾语从句中that不可以省略 ii 一个句子有两个或多个并列的宾语从句时，引导第二个和以后几个句子中的that不可以省略 iii 与动词相隔的宾语从句，不可以省略 iv that引导的宾语从句放在句首时，不可以省略二. 主语从句1、主语从句：作句子主语的从句叫主语从句。主语从句通常由下列词引导：1）从属连词that，whether 等；2）连接代词what，who，which，whatever，whoever，whom 等；3） 连接副词how，when，w
2、here，why 等。2、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。注：whom、who指人，what指物，whatever，whoever表示泛指意义。例如：What he wants to tell us is not clear. Who will win the match is still unknown. It is known to us how he became a writer. Where the English evening will be held has not yet been ann
3、ounced. 注意：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：It is a fact that 事实是 It is an honour that 非常荣幸 It is common knowledge that 是常识 It is a pity that 遗憾 （2）It + be + 动词的过去分词+ that从句: It is said that 据说 It is reported that 据报道 It has been proved
4、 that 已经证明 It is believed that 人们认为 It is supposed that 据猜测（3）It + 不及物动词（vi） + that 从句： It seems that 似乎 It happened that 碰巧 It appears that 似乎（4）It + be + 形容词 + that从句 It is natural that 很自然 It is strange that 奇怪的是 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 （imp
5、ortant, natural, strange, etc.） that It is suggested （requested, proposed, desired, etc.） that3、It 作形式主语和it引导强调句的比较It 作形式主语代替主语从句，主要是为了平衡句子结构，主语从句的连接词没有变化。it引导的强调句则是对句子某一部分进行强调，无论强调的是什么成分，都可用连词that引导，被强调部分指人时也可用who/whom。 a） It is a pity that you didnt go to see the film. b） It doesnt interest me whe
6、ther you succeed or not. c） It is in the morning that the murder took place.（强调句型） d） It is John that broke the window.（强调句型）4、注意：since, if 不能引导主语从句，但当it做形式主语，主语从句放在句末时，if, whether均可5、主语从句不可位于句首的五种情况：（1）if 引导的主语从句不可居于复合句句首。（2）It is said /reported结构中的主语从句不可提前。 正确表达：It is said that President Jiang wil
7、l visit our school next week. 错误表达：That President Jiang will visit our school next week is said. （3）It happens/occurs结构中的主语从句不可提前。It occurred to him that he failed in the examination.That he failed in the examination occurred to him.（4）It doesnt matter how/whether 结构中的主语从句不可提前。It doesnt matter wheth
8、er he is wrong or not.Whether he is wrong or not doesnt matter.（5）含主语从句的复合句是疑问句时，主语从句不可提前。Is it likely that it will rain in the eveningIs that will rain in the evening likely6、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。 a） What you said yesterday is right. b） That she is stil
9、l alive is a consolation三、表语从句表语从句：在复合句中，位于系动词之后作表语的从句叫表语从句。引导表语从句的关联词与引导主语从句的关联词大致一样，表语从句位于连系动词后，有时用as if引导。可以接表语从句的系动词有be ,look , remain（保持）, seem等常用的还有the reason is that It is because It appears/seems that It happens that It turns out that（结果是.）等结构由从属连词，连接代词，连接副词引导，其中that常常可以省略由as if， as though 引
10、导 It looks as if It seems as ifwhy, because 都可以引导表语从句，但why强调结果，because强调理由当主语为suggestion, order, requirement, advice, request, demand 等这类名词时，表语从句用虚拟语气（should）doif不能引导表语从句注意：当主语是reason时，表语从句要用that引导而不是because。The reason why he was late was that he missed the train by one minute this morning .【注意】whet
11、her 可引导表语从句，但与之同义的if却通常不用于引导表语从句。四、同位语从句1、同位语从句说明其前面的名词的具体内容。同位语从句通常由that引导，that不可以省略 由whether引导，不可用if2、可用于同位语从句的名词有belief、advice、demand、doubt（怀疑）、possibility、though、proposal、case、fact、hope、idea、information、message、news、order、problem、promise、question、request、suggestion、truth、wish、word等。The news that
12、 we won the game is exciting. I have no idea when he will come back home. The thought came to him that Mary had probably fallen ill. 3、在no idea后用wh-疑问词引导4、 同位语从句与定语从句的区别（1） 定语从句中的that既代替先行词，同时以在从句中作某个成分（主语或宾语），而同位语从句中的that是连词，只起连接主句与从句的作用，不充当句中任何成分。（2） 定语从句是形容词性的，其功能是修饰先行词，对先行词加以限定，描述定的性质或特征；同位语从句是名
13、词性的，其功能是对名词进行补充说明。1） The news that he told me is that Tom would go abroad next year.（他告诉我的消息是汤姆明年将出国。）（第一个that引导的从句是定语从句，that在从句中作宾语）2）The news that Tom would go abroad is told by him.（汤姆将出国的消息是他讲的。）（同位语从句，that在句中不作任何成分）五、宾语从句宾语从句：名词从句用作宾语的从句叫宾语从句。由从属连词、连接代词、连接副词引导。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
14、，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。He has told me that he will go to Shanghai tomorrow. We must never think （that） we are good in everything while others are good in nothing. 在demand、order（命令）、suggest、decide、insist（坚持）, desire, urge，advice，propose，require，request, command（命令）,
15、doubt等表示要求、命令、建议、决定等意义的动词后，宾语从句常用“（should）+ 动词原形”。I insist that she （should） do her work alone. The commander ordered that troops （should） set off at once. 2. 用who，whom, which, whose, what, when, where, why, how, whoever, whatever, whichever等关联词引导的宾语从句相当于特殊疑问句，应注意句子语序要用陈述语序。I want to know what he ha
16、s told you. She always thinks of how she can work well. She will give whoever needs help a warm support. 3. 用whether或if引导的宾语从句，其主语和谓语的顺序也不能颠倒，仍保持陈述句语序。此外，whether与if 在作“是否”的意思讲时在下列情况下一般只能用whether，不用if：a. 引导主语从句并在句首时；b. 引导表语从句时；c . 引导从句作介词宾语时；d. 从句后有“or not”时；e. 后接动词不定式时。Whether there is life on the m
17、oon is an interesting question.Everything depends on whether we have enough money. I wonder whether he will come or not. Can you tell me whether to go or to stay 4. 注意宾语从句中的时态呼应，当主句动词是现在时，从句根据自身的句子情况，而使用 不同时态。I know （that） he studies English every day. （从句用一般现在时） I know （that） he studied English las
18、t term. （从句用一般过去时） I know （that） he will study English next year. （从句用一般将来时） I know （that） he has studied English since 1998. （从句用现在完成时） 当主句动词是过去时态（could, would除外），从句则要用相应的过去时态，如一般过去时，过去进行时，过去将来时等；当从句表示的是客观真理，科学原理，自然现象，则从句仍用现在时态。The teacher told us that Tom had left us for America 5. think, believe,
19、 imagine, suppose，guess, expect, fancy, consider等等动词引起的否定性宾语从句中，要把上述主句中的动词变为否定式。即将从句中的否定形式移到主句中。We dont think you are here. 我们认为你不在这。I dont believe he will do so. 我相信他不会这样做。6、后面不能接that从句的动词有：condemn谴责，判刑 force强迫 take拿走 forgive原谅 dislike不喜欢 refuse拒绝 let like love help admire羡慕 allow celebrate cause注：
20、以上动词后不能接that从句，但可以用不定式，动名词做宾语。六、whether与if 均为是否的意思。但在下列情况下，只可用whether：1. whether引导主语从句并在句首时，只能用whether，当it做形式主语，主语放句首时，whether，if均可 eg:whether he can come to the party on time depends on the traffic 2. 引导表语从句 The question is whether we can get in touch with her 3. whether从句作介词宾语 :It depends on wheth
21、er he will come.与whether都可以与or not 连用，但后面紧跟or not 时只能用whether We didnt know whether or not she was ready.（此时只能用whether）I wonder whether/if the news is true or not.（此时则二者都可以用） 5. 引导同位语从句 Whether he will come is not clear.6.后接不定式时Eg I dont know whether to go.7.在discuss后只能用whether （1）大部分连接词引导的主语从句都可以置于
22、句末，用 it充当形式主语。It is not important who will go. It is still unknown which team will win the match. （2）whether从句中不能有否定式，而if可以 I dont care if he doesnt come.七、名词性that-从句（1）由从属连词that引导的从句叫做名词性that-从句。That只起连接主句和从句的作用，在从句中不担任任何成分，本身也没有词义。名词性that-从句在句中能充当主 语、宾语、表语、同位语和形容词宾语，例如：主语：That she is still alive i
23、s her luck.她还活着全靠运气。宾语：John said that he was leaving for London on Wednesday.约翰说他星期三要到伦敦去。表语：The fact is that he has not been seen recently.事实是近来谁也没有见过他。同位语：The fact that he has not been seen recently disturbs everyone in his office. 近来谁也没有见过他，这一事实令办公室所有的人不安。形容词宾语：I am glad that you are satisfied wi
24、th your job. 2）That-从句作主语通常用it作先行词，而将that-从句置于句末，例如：It is quite clear that the whole project is doomed to failure.很清楚，整个计划注定要失败。Its a pity that you should have to leave.你非走不可真是件憾事。用it作形式主语的that-从句有以下四种不同的搭配关系：a. It + be +形容词+ that-从句 It is necessary that有必要 It is important that重要的是 It is obvious tha
25、t很明显 b. It + be + -ed 分词+ that-从句 It is believed that人们相信 It is known to all that众所周知 It has been decided that已决定 c. It + be +名词+ that-从句 It is common knowledge that是常识 It is a surprise that令人惊奇的是 It is a fact that事实是 d. It +不及物动词+ that-从句 It appears that似乎 It happens that碰巧 It occurred to me that我突
26、然想起 八、名词性wh-从句1）由wh-词引导的名词从句叫做名词性wh-从句。Wh-词包括who, whom,. whose, whoever, what, whatever, which, whichever等连接代词和where, when, how, why等连接副词。Wh-从句的语法功能除了和that-从句一样外，还可充当介词宾语、宾语补语和间接宾语等，例如： How the book will sell depends on its author. 直接宾语：In ones own home one can do what one likes. 间接宾语：The club will
27、give whoever wins a prize. 俱乐部将给得胜者设奖。 My question is who will take over president of the Foundation. 宾语补足语：She will name him whatever she wants to. I have no idea when he will return. Im not sure why she refused their invitation. 介词宾语：That depends on where we shall go. 2）Wh-从句作主语也常用先行词it做形式主语，而将wh-从句置于句末，例如：It is not yet decided who will do that job. It remains unknown when they are going to get married. 九、if, whether引导的名词从句1）yes-no型疑问从句从属连词if, whether引导的名词从句是由一般疑问句或选择疑问转化而来的，因此也分别被称为yes-no型疑问句从句和选择型疑问从句，其功能和wh-从句的功能相同， 例如：Whe
