1、语法剖析名词性从句(一)在复合句中起名词作用的从句叫做名词性从句。它包括主语从句、宾语从句，表语从句和同位语从句。名词性从句是中学阶段的一个重要语法项目，在历年的高考中几乎都有涉及，因此我们必须好好掌握它。本单元我们主要学习宾语从句和表语从句。下面我们就来看看：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宾语从句宾语从句在主从复合句中充当宾语。引导宾语从句的关联词与引导主语从句、
2、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 在句中不担当任何成分，在口语或非正式的文体中常被省去。如：We all agreed(that) it would be a mistake not to take his advice.我们都认为不听他的意见将是个错误。注意以下几点：从句是并列句时,第二个分句前的 that 不可省。如：We all think (that) she is working very hard and that she will surely go to a
3、 very good university.我们都认为她学习非常努力，一定能进一个非常好的大学。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”。如：The commander ordered that troops (should) set off at once.司令员命令部队马上出发。动词+it+形容词或惯用搭配 +that 从句。We think it important that every citizen sho
4、uld have good manners.我们认为每个市民有礼貌是很重要的。(其中 it 为形式宾语，而真正的宾语就是 that 引导的从句。)注意动词 doubt 的否定结构才可以接 that 从句。如：I dont doubt that he will be against the idea.我毫不怀疑他会反对这一想法。 I doubt whether he will be against the idea.我怀疑他是否会反对这一想法。2.wh-疑问词引导的宾语从句用 who，whom,which,whose,what,when,where,why,how,whoever,whateve
5、r,whichever 等关联词引导的宾语从句相当于特殊疑问句，连接词都在从句中担当一定的成分。应注意句子语序要用陈述语序。如：She always thinks of how she can work well.她总是在想怎样能把工作做好。3.whether 或 if 引导的宾语从句用 whether 或 if 引导的宾语从句，从句仍保持陈述句语序， whether 或 if 不担当成分。如：I wonder whether he will come or not.我想知道他来还是不来。此外，whether 与 if 作“ 是否 ”讲时，在下列情况下一般只能用 whether，不用 if：a
6、.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。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。如：I know that he studied English last term.(从句用一般过去时) 我知道他上学期学过英语。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、过去完成时等；但是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。如：The teacher told us that
7、Tom had left us for America.老师告诉我们汤姆已经离开我们去美国了。5.think,believe,imagine,suppose 等动词引起的否定性宾语从句中，要把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。如：We dont think you are here.我们认为你不在这儿。表语从句在句中作表语的从句叫表语从句,表语从句位于系动词后。1.that 引导的表语从句that 仅起连接作用，无意义，在句中不作任何成分，通常不能省略。这种从句往往对主句主语的内容起进一步解释的作用。其基本结构为主语+系动词+that 从句。如：What surprise
8、d me most was that all the pupils were unusually quiet.使我十分惊讶的是所有的学生异乎寻常的安静。当主语是 reason 时，表语从句要用 that 引导而不是 because。如：The reason why he was late was that he missed the train by one minute this morning.2.wh-疑问词引导的表语从句连接代词 what，which ，who，whom，whose 除在句子中起连接作用外，还可在从句中充当主语、宾语、表语、定语，且各有各的词义。如：The proble
9、m is who is really fit for the hard job.问题是谁才真正适合做这份艰苦的工作。(who 在从句中作主语 )Tom is no longer what he used to be.汤姆不再是以前的汤姆了。(what 在从句中作系动词 be 的表语 )连接副词 when,where,how,why 除在句中起连接作用外，在从句子中还充当时间，地点，方式，原因状语，本身具有词义。如：Thats where I cant agree with you.那就是我不能同意你的地方。whether 引导的表语从句连接词 whether 起连接作用，意为“是否，究竟，到底
10、”(注意：if 不能引导表语从句)，在句中也不作任何 成分。如：The question is whether that man will turn up in time.问题是那个人是否会及时出现。3.其他连词 as if,because,as,as though 引导的表语从句because 引导表语从句通常只用于“This/That/It is/was because.”结构中。as if/as though引导的表语从句常置于系动词 look，seem ，sound，be，become 等后面，常用虚拟语气，表示不存在的动作或状态。如：The elephant feels as if/
11、though he were a wall.大象摸起来像一堵墙。4.主语是表示建议、命令、要求等的名词，那么表语从句应该用虚拟语气，即 should后接动词原形,(should 可以省略) 。如：His suggestion is that we (should) climb all the way to the top of the hill. 他的建议是我们应该一路爬到山顶。宾语从句和表语从句典型用法正误辨析 1.我们不知道下一步该怎么做。错误：We wonder how we shall do next.正确：We wonder what we shall do next.辨析：what
12、，how 都可以引导宾语从句，how 在从句中充当状语，而 what 在从句中充当主语、宾语或表语。2.请你告诉我他们在哪里野餐？错误：Could you tell me where are they having a picnic?正确：Could you tell me where they are having a picnic?辨析：不管主句是陈述句是疑问句，宾语从句都应该用陈述语序。3.我们相信他们已经提前完成他们的任务了，是吗？错误：We believe that they have finished their task ahead of time,dont we? 正确：We
13、believe that they have finished their task ahead of time,havent they? 辨析：以think，believe，consider，suppose 等动词加 that 引导的宾语从句，如果主句的主语是第一人称 I/we,反意疑问句应根据从句来提问；如果主语是第二或第三人称的话，则反意疑问句应根据主句来提问。4.现在我们面临的问题是我们城市的废物该如何处理。错误：The problem we are facing is that the waste in our city should be dealt with.正确：The pro
14、blem we are facing is how the waste in our city should be dealt with. 辨析:表语从句可以用 that 引导，也可以用连接代词 what， who，whom，which，whose 等以及连接副词 how，where，when，why 来引导。根据句意，此句用 how 来引导，并作 deal with 的状语。5.李先生看起来好像十分精通维修电脑。错误：Mr Li seems that he is very expert at repairing computers.正确：Mr Li seems as if he is ver
15、y expert at repairing computers.辨析：seem/look 所需接的表语从句应该用 as if/although 引导，也可用 it seems that 句式，但是 that 所引导的是主语从句。如：The bridge looks as if it will be broken soon.It seems that they have been to the United States before.6.对不起我不知道你也想参加那个竞赛。错误：Im sorry that I dont know you want to take part in that com
16、petition. 正确：Im sorry that I didnt know you wanted to take part in that competition. 辨析：Im sorry 引导的宾语从句中通常用过去时态，说明对已经发生的事情道歉。7.那个人所提出的问题是这项工程是否能按期完工。错误：The question which the man raised was if the project could be completed on time.正确：The question which the man raised was whether the project could
17、be completed on time.辨析:if 和 whether 都可以引导名词性从句表示 “是否”，但是 if 通常只能引导宾语从句，而 whether 则可以引导宾语从句、主语从句和表语从句等，并且 whether 可以与 or not 连用。8.那就是那些旅客没能到达山顶看日出的原因。错误：That was because those passengers couldnt go to the top of the mountain to see the sunrise.正确：That was why those passengers couldnt go to the top o
18、f the mountain to see the sunrise.辨析：that/this/it is because 用于说明前面发生事情的原因，而 that/this/it is why 则用于说明前面发生事情的结果。9.那位老人终于弄清楚他在何时何地丢了他的雨伞。错误：The old man finally found out when or where he had lost his umbrella. 正确：The old man finally found out when and where he had lost his umbrella. 辨析：此处时间和地点为并列存在，应
19、该用 and 连接，when and where 共同引导一个宾语从句，实际上是两个宾语从句 when he had lost his umbrella and where he had lost his umbrella 的省略形式。10.我的建议是政府应当削减卷烟的产量。错误：My suggestion is the government should cut off the production of cigarettes. 正确：My suggestion is that the government should cut off the production of cigarettes.辨析：表语从句中的连词 that 通常不可以省略，而宾语从句中的连词 that 则可以省略。
