1、人教课标高一 必修 3 Unit 4主语从句在复合句中作句子的主语。引导主语从句的词有从属连词that,whether,if；连接代词who,whoever,whom,what,whatever,whose,which；连接副词when,where,how,why等。【例句呈现】观察下列例句，指出其中所包含的主语从句及引导词:1.What is needed for a long trip is careful preparation.该句中主语从句是 _，引导词为 _。What is needed for a whatlong trip2.That Jay Zhou will come to
2、 my city excites everybody.该句中主语从句是 _ _，引导词为 _。3.Whether we will travel abroad or not has not been decided.该句中主语从句是 _ _，引导词为_。That Jay Zhou willWhether we willcome to my city thattravel abroad or notwhether4.Whoever knows the secret mustnt tell others.该句中主语从句是 _ _，引导词为 _。5.It remains a puzzle why di
3、nosaurs died out suddenly long time ago.该句中主语从句是 _，引导词为_。Whoever knows the whoeverwhy dinosaurs diedwhysecretout suddenly long long ago【观察总结】通过分析上面例句，同学们可能会发现上面第5句中的主语从句似乎比较隐蔽。其实，这也是主语从句的一种呈现方式，即：当一个句子主语过长时，可以用it作形式主语，而把真正的主语或主语从句后移至句子末尾，以保持句子的平衡。注意观察下列例句中的划线部分：It is not clear how the accident happe
4、ned.It is not hard to understand why he did so at that time.It is a pity that you should have made such a careless mistake.It is reported that more than thirty deaths were caused in the accident.不难看出，虽然上面例句中都用it作形式主语，但句子结构却不尽相同。现将常见的由it作形式主语的句型总结如下：1.It is+n.+that 从句2.It is+adj.+that 从句，常见此类形容词有：imp
5、ortant,necessary,clear,certain,natural,strange,obvious,likely,impossible,possible 等。3.It+特殊动词+that 从句It seems/appears.that.似乎It happened(to sb.)that.（某人）碰巧4.It+be+过去分词+主语从句It is said/reported/believed/suggested/known/proved that.【要点精讲】1.what 与 that 引导主语从句观察下列例句，试着翻译例句并总结其规律。(1)What you lack is self-
6、confidence.译为：_你所缺乏的是自信。(2)That more and more students are admitted into universities is true.译为：_ _(3)What is needed for the program is more wisdom.译为：_这个项目所需要的是更多的智慧。越来越多的学生将被大学录取的消息是真实的。从上面例句可以看出，that引导主语从句时，在句中具有“两不”原则：一、不作句子成分；二、没有实际意义。当它引导的主语从句置于句首时，that不能省略；如果用it作形式主语，而把主语从句放在句末时，that可以省略。而wh
7、at引导的从句则恰恰相反，what在从句中的作用为：一、作句子成分；二、除了起到引导从句的作用外还要承担具体的意义。【巩固练习】用 what 或 that 填空。(1)_ he told us this morning was just a lie.(2)_ is important to us is enough time.(3)It worries my mom _ she is beginning to get a little fat.(4)_ we cant get seems better than _ we have.WhatWhatthatWhatwhat2.whether 与
8、 if 引导主语从句如果主语从句置于句首，不能用if引导，此时，需用whether。但如果用it作形式主语，而把主语从句放在句末时，也可以用if引导。【巩固练习】用 whether 或 if 填空。(1)It doesnt matter _ he will come or not.(2)_ well go camping tomorrow depends on the weather.(3)It was doubtful _ Tom really saw Sharon.(4)_ Tom really saw Sharon was doubtful.whetherWhetherwhether/i
9、fWhether3.其它引导词连接代词who,which,whom,whose有各自的具体意义，起连接作用，同时在从句中充当主语、宾语、表语、定语等；whoever,whatever,whichever在意义上更为强调，常译为“无论”；连接副词when,where,why,how等也有各自的意义，起连接作用，并在从句中作状语。【常见错误展示】下列各句均有一处错误，请改正并分析错误的原因。1.Light travels faster than sound is common knowledge.Thatthat 虽无词义但引导主语从句位于句首时不能省略。if,whether 都可表示“是否”,但
10、if不能引导位于主句之前的主语从句，它可以引导位于主句之后带有形式主语it的主语从句。2.If shes coming or not doesnt matter much.Whether3.That the professor said is of great importance.4.Where will the trees be planted has not been decided.Whatthat 引导主语从句时无词义。What the professor said表示“教授所说的”。将will置于trees之后。主语从句要用陈述句语序。5.No matter who breaks
11、the rule will be punished.6.When and where the meeting will be held still remain a question.引导让步状语从句时二者可互换，但引导名词性从句时只能用whoever。Whoever 主语从句表示单一概念时，谓语要用单数形式。remains7.What were your problems a year ago has now become mine.8.It was requested that everyone made a speech at the meeting.has 要改为 have。主语从句表示复数概念时，谓语要用复数形式。have在“It is requested/ordered/suggested+that从句”中，从句要用虚拟语气，即谓语用“should+动词原形”，should可省略。(should)make
