精选优质文档-倾情为你奉上语法要点剖析一、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, why1. 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.) that2. 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。注意：在demand、order、suggest、decide、insist, desire, demand, request, command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”。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 want 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。 Everything depends on whether we have enough money. 一切要看我们是否有足够的钱。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. 我相信他不会这样做。3. 表语从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。That is why he didnt come to the meeting. 那就是他为什么不到会的原因。It 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选择：1. “Is Mary from New York City” “I dont know _.”A. from what city does she come from B. from what city she comeC. what city does she come from D. what city she comes from2. _ makes mistakes must correct them.A. What B. That C. Whoever D. Whatever3. The reason why I didnt go to Shanghai was _ a new job.A. because I got B. because of getting C. I got D. that I got4. It worried her a bit _ her hair was turning grey.A. while B. that C. if D. for 5. Henry killed the dog. Ill ask him why _.A. did he do that B. he did thatC. he did D. he has done so 6. Have you seen Henry lately My boss wants to know _.A. how he is getting along B. how is he getting alongC. what he is getting along D. what is he getting along7. It is generally considered unwise to give a child _ he or she wants.A. however B. whatever C. whichever D. whenever8. He asked me _ with me.A. what is the trouble B. what wrong wasC. what was the matter D. what trouble it is9. I am sure _ he said is true.A. that B. about that C. of that D. that what10. I wonder how much _.A. does the watch cost B. did the watch costC. the watch costed D. the watch costs11. Mary is _ someone might recognize her.A. afraid of B. afraid about C. afraid that D. afraid for12. I dont doubt _ hell come.A. that B. if C. what D. whether13. “Why did you go to the wrong class, Mr. Wang”“Well, I forget _ I was supposed to go to.”A. which the room B. which room C. what was the room D. what room was it14. _ surprised me most was