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1、在句子中起名词作用的句子叫名词从句 (Noun Clauses)。 名词从句的功能相当于名词词组, 它在复合句中能担任主语、宾语、表语、同位语、介词宾语等,因此根据它在句中不同的语法功能,名词从句又可分别称为主主语语从从句句、宾宾语语从从句句、表表语语从从句句和和同同位位语语从从句句 。 一一、引引导导名名词词性性从从句句的的连连接接词词引引导导名名词词性性从从句句的的连连接接词词可可分分为为三三类类: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连接代词: wha
2、t, whatever, who, whoever, whom,whose, which.whichever,whomever连接副词: when, where, how, why不不可可省省略略的的连连词词 :1. 介词后的连词2. 引导主语从句和同位语从句的连词不可省略。That she was chosen made us very happy.We heard the news that our team had won.比比较较:whether 与 if 均为“是否“的意思。 但在下列情况下, whether 不能被 if 取代:1. whether 引导主语从句并在句首2. 引导表
3、语从句 3. whether 从句作介词宾语4. 从句后有“or not“ Whether he will come is not clear.大部分连接词引导的主语从句都可以置于句末,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. 二二. 主主语语从从句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
4、,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。Who will win the match is still unknown. 谁能赢得这场比赛还不得而知。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 an
5、nounced. 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 从句另另注注意意在在主主语语从从句句中中用用来来表表示示惊惊奇奇、不不相相信信、惋惋惜惜、理理应应如如此此等等语语气气时时,谓谓语语动动词词要要用用虚虚拟拟语语气气 “(should) +do”,
6、常常用用的的句句型型有有: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三三、宾宾语语从从句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
7、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。注意:在 demand、order、suggest、decide、insist, desire, request, command 等表示要
8、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”。例如:I insist that she (should) do her work alone. 我坚持要她自己工作。The commander ordered that troops (should) set off at once. 司令员命令部队马上出发。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。例如:I wa
9、nt to know what he has told you. 我想知道他告诉了你什么。 She always thinks of how she can work well. 她总是在想怎样能把工作做好。She will give whoever needs help a warm support. 凡需要帮助的人,她都会给予热情的支持。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
10、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。例如:Whether there is life on the moon is an interesting question. 月球上有没有生命是个有趣的问题。The question is whether she should have a low opinion of the test?Everything depends on whether we have enough money. 一切要看我们是否有足够的钱。I wonder whether he will come or not. 我想
11、知道他来还是不来。Can you tell me whether to go or to stay? 你能否告诉我是去还是留?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。例如:he studies English every day. (从句用一般现在时)he studied English last 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)he has studied English since 1998. (从句用现在完成时)当主句动词是
12、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。例如:The teacher told us that Tom had left us for America 5. think, believe, imagine, suppose 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。例如:We dont think you are here. 我们认为你不在这。I dont believe he will do so. 我相
13、信他不会这样做。 四四、表表语语从从句句在句中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。其基本结构为:主语 + 系动词 + that 从句。例如:The fact is that we have lost the game. 事实是我们已经输了这场比赛。Thats just what I want. 这正是我想要的。This is where our problem lies. 这就是我们的问题所在。That is why he didnt come to the meeting. 那就是他为什么不到会的原因。I
14、t looks as if it is going to rain. 看上去天要下雨了。需要注意的,当主语是 reason 时,表语从句要用 that 引导而不是 because。例如:The reason why he was late was that he missed the train by one minute this morning .【注意】whether 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。 五五、同同位位语语从从句句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,可用于同位语从句的名词有 advice、demand、doubt
15、、fact、hope、idea、information、message、news、order、problem、promise、question、request、suggestion、truth、wish、word 等。例如:The news that we won the game is exciting. 我们赢得这场比赛的消息令人激动。I have no idea when he will come back home. 我不知道他什么时候回来。The thought came to him that Mary had probably fallen ill. 他想到可能玛丽生病了。同同位
16、位语语从从句句和和定定语语从从句句的的区区别别: that 作为关系代词,可以引导定语从句,充当句子成分,在从句中作宾语时可以省略; that 引导同位语从句时,起连词的作用,没有实际意义,不充当句子成分,一般不能省略。 试比较下面两个例句 : I had no idea that you were here(that 引导同位语从句,不能省略)Have you got the idea(that)this book gives you of life in ancient Greece?(that 引导定语从句,作宾语,可以省略) 六六、名名词词性性 that-从从句句1)由从属连词 that 引导的从句叫做名词性 that-从句。 That 只只起起连连接接主主句句和和从从句句的的作作用用,在在从从句句中中不不担担任任任任何何成成分分,本本身身也也没没有有词词义义。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 he is still alive is s