2017初三英语重要知识点：主语从句.doc

2017初三英语重要知识点：主语从句 2017初三英语重要知识点：主语从句主语从句用作主语的从句叫主语从句。(That the earth goes around the sun) is known to all.(How this happened) is not clear to anyone.(Whoever comes) is welcome.(When we shall have our sports meeting) is still a question.(Whether he will come today) is still unknown.注意：1. 主语从句是特殊疑问句，应该用特殊疑问词加陈述句语序。2. that引导的主语从句放在句首，不可省略that。3. 主语从句常用it作形式主语，真正的主语放在后面，这时that可省略。Its a pity (that) you missed such a good opportunity.Its still a question when we shall buy the new equipment.Its still unknown whether he will come or not.4. It is + P.P.+ that ; It + Vi + that，It作形式主语。It is said that the president will visit our company.It seems that he has caught a cold.主语从句：在复合句中充当主语成分的句子叫做主语从句。常规主语从句，即句子在复合句中充当一个主语。 主语从句的时态：不受主句的时态影响和限制。例如：That he finished writing the composition in such a short time surprised us all.What we need is time.It is certain that he will win the match.(1) 引导主语从句连词有that,whether,who,what,whatever等(2) 连词位于句首不能省略(3) 主语从句大多数情况下视为第三人称单数主语从句引导词：1、由连词that引导的主语从句。例如：That you will win the medal seems unlikely.你想获得奖牌看起来是不可能的。That you are so indifferent bothers me.你如此冷淡使我很烦恼。That she survived the accident is a miracle.她在事故中幸免于难简直是奇迹。2、用连接代词或连接副词if, whether 引导的主语从句。例如： Which of them escaped from the prison is still a mystery.他们哪一个是从监狱里逃跑的，仍然是个谜。When they will come hasnt been made pubic.他们什么时候来还不知道。Whether she is coming or not doesnt matter too much.她来不来都无关紧要。3、用关系代词引导的主语从句。例如：What you need is more practice.你所需要的是更多的训练。What I want to know is this. 我想知道的就是这事。Whatever we do is to serve the people.我们无论做什么都是为人民服务。4、主语从句可以直接放在主语位置上，也可以用it作形式主语，而将从句放在句末（尤其是当谓语较短时）。例如：That light travels in straight lines is known to all.光沿直线传播，这是众所周知的事。=It is known to all that light travels in straight lines.众所周知光沿直线传播。When the plane is to take off has not been announced .飞机何时起飞还没有宣布。= It has not been announced when the plane is to take off.还没有宣布飞机何时起飞。当what引导的主语从句表示“的东西”时，一般不用it作形式主语。错:It is a book what he wants.对:What he wants is a book. 他想要的是本书。如果带主语从句的句子是疑问式，则必须用it作形式主语的结构。例如：Has it been settled who will be sent to carry out the task ?谁将被派去执行这项任务决定了吗 ？主语从句与宾语从句区别：主语从句与宾语从句两者的用法和在句中的作用是不同的，下面从它们的各自用法来介绍。一主语从句主语从句 定义：在句子中担当主语的是一个从句，这个从句就叫做主语从句。主语从句是在复合句中充当主语的从句，通常放在主句谓语动词之前或由形式主语it代替，而本身放在句子末尾。1. It 作形式主语和it引导强调句的比较主语从句常用it作形式主语，一般常用句型为：It is+名词/形容词/过去分词+主语从句例如：It is still a question whether she will come or not.It is strange that you should like him.It is still unknown which team will win the match.另外，还有一些比较多见的结构：It turned out that;It has been proved that;It happened/occurred that;It is well-known that等等而强调句则不同，它的结构是：It+be+被强调部分+that+从句强调主语：It is the times that produce their heroes.时势造英雄强调宾语：It is English that Prof.Lin teaches us.强调状语：It was in shanghai that I saw the film.判断是否是强调句有一个方法，就是将that以后的“句子的其余部分”拿出来单独看，看有没有缺成分，缺的是什么成分，再把谓语动词后面that前面的那部分，带到你认为缺成分的地方，如果放进去是一句完整的句子了，那就说明是强调句。2. 用it 作形式主语的结构(1) It is +名词+that从句It is a fact that 事实是It is an honor that 非常荣幸It is common knowledge that 是常识(2) it is +形容词+that从句It is natural that 很自然It is strange that 奇怪的是(3) it +不及物动词+that从句It seems that 似乎It happened that 碰巧(4) it is+过去分词+that从句It is reported that 据报道It has been proved that 已证实3.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。例如：It is said that President Jingo will visit our school next week.(3) It happens, It occurs 结构中的主语从句不可提前。例如：It occurred to him that he failed in the examination.(4) It doesnt matter how/whether 结构中的主语从句不可提前。例如：It doesnt matter whether he is wrong or not.(5) 含主语从句的复合句是疑问句时，主语从句不可提前。例如：Is it likely that it will rain in the evening?4. What 与that 在引导主语从句时的区别What 引导主语从句时在从句中充当句子成分，如主语宾语表语，而that 则不然。例如：What you said yesterday is right.宾语从句用以区分主语从句的几个特征：1、引导词：whatwhichwhosewhenwhetherifwhere2、语序：宾语从句必须是用陈述语句。如：I think that you must work harder.宾语从句的引导词、连接词的区别、否定转移等现象。(1)表达时间的几个句型：一般用when或者是what time：What time will the train leave?由于时刻都是固定的，也可以用一般现在时代替一般将来时：What time does the train leave?(2)时间的表达方式：8：19(nineteen past eight),7:57(three to eight)，在时间的中间也可以加上分的单词(minutes)(3)had better +动词原型。意思是提要求，建议。但是上下级不能用这种方式，因为语气太重：You had better give up smoking .(4)sb leave sth +地点I left my book in my classroom yesterday.(5)may I have your name(addressage)?一般询问对方的年龄、名字等，不要习惯以前的问法，这样很不礼貌，而是要采访上面的问法。以前的习惯是：how old are you? whats your name?(6)修饰名词的代词次序：限-描-大-形-年-颜-籍-物-类+名词：this is a bridge.This is a beautiful bridge补充：从句的语序永远是陈述句。主语从句结构：1、It is +名词+从句It is a fact that 事实是It is good news that 是好消息It is a question that 是个问题It is common knowledge that 是常识类似的名词还有：a pity；a wonder；a good thing； no wonder； surprise等。例如：It is a mystery to me how it all happened.这一切是怎么发生的是个谜。It is common knowledge that the whale is not a fish.鲸鱼不是鱼，这是常识。It is no surprise that Bob should have won the game.鲍勃会赢得这场比赛，这不足为奇。2、It is +形容词+从句It is necessary that 有必要It is clear that 很清楚It is likely that 很可能It is important that 重要的是类似的形容词还有：strange; natural; obvious; true; good; wonderful; possible; unlikely; quite; unusual; certain; evident; worth-while; surprising; interesting; astonishing, etc.例如：It is obvious that conductors and insulators are both important in industry.很明显导体和绝缘体在工业中都很重要。It is doubtful whether she will be able to come.她是否能来令人怀疑。It was really astonishing that he refused to talk to you .他拒绝和你说话真是令人惊讶。It is essential that he should be here by the weekend .周末之前，他应该到这里是必要的。It seems obvious that we can not go on like this.很明显我们不能这样下去了。3、It is +过去分词+从句It is said that 据说It is reported that 据报道It has been proved that 已证明It must be proved that 必须指出类似的过去分词还有：known; estimated; expected; believed; thought; hoped; noted; discussed; required; decided; suggested; demanded; made clear; found out,etc.例如：It is thought that he is the best player.大家都认为他是最好的选手。It is estimated that the vase is 2000 years old.据估计这个花瓶有2000年的历史。It is used to be thought that a new star must be due to a collision between two stars.过去一直认为新星是由于两颗星星之间碰撞产生的。It has not been made clear when the new road is to be opened to traffic.还没弄清楚这条路将开始通车。4、It +不及物动词+从句It seems that 好像是It happened that 碰巧It follows that 由此可见It has turned out that 结果是类似的不及物动词还有：seem, appear, occur, follow, happen, turn out, etc.例如：It turned out that nobody remembered the address.结果是无人记得那个地址。It now appears that they are in urgent need of help.看起来他们急需帮助。It does not matter if I missed m