三大从句语法讲解
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三大从句语法讲解
从句:在复合句具有主谓部分但不能独立成句的句子。
主句:除掉从句,就是主句
在英语中,主要有三大从句:
名词性从句(包括主语从句,宾语从句,表语从句,同位语从句)
形容词性从句(即定语从句)
副词性从句(即状语从句:包括时间、条件、结果、目的、原因、让步、地点、方式等)
三大从句快速判断方法:
1.主句不完整,从句不完整→名词性从句(连接代词)
2.主句不完整,从句完整→名词性从句(连词、连接副词)
3.主句完整,从句不完整→定语从句(关系代词)
4.主句完整,从句完整→定语从句(关系副词)、同位语从句、状语从句
名词性从句
主语从句:(用句子代替名词来做主语)
比如汉语中:①你通过我的方法学好了英语【主语】是我的荣幸。
②你要不要学英语【主语】是你自己的事。
③你想要的学习效果【主语】还必须靠你自己实现。
④你什么时候开始学英语【主语】是很重要的一件事。
基本:三类主语从句的连词
(1)从属连词引导的主语从句(that / whether / if)
that引导的主语从句:引导词that无含义/在句中不做成分/不可以省。That 引导主语从句通常用it 作形式主语。
例如:That you will win the medal seems unlikely.(你要赢得这样比赛看起来不可能。)
That she survived the accident is a miracle.(她能在这场事故中幸存真是个奇迹。)
这个就同我们汉语例子中的①句一样,只不过英语中更加重视句子结构,所以把that放在前头,告诉你这个that后面跟的句子(和里面的主谓宾)不影响主句。
whether 引导的主语从句: whether有含义(是否)/在句中不做成分/不可以省。
注意:引导主语从句,不能用if不能在开头,只能用whether.
Whether we will hold a party in the open air tomorrow depends on the weather.
(我们明天会不会在户外举办聚会取决于天气。)
Whether she is coming or not doesn’t matter too much.
(她会不会来都没多大关系。)
这个就同我们汉语例子中的②句一样,whether就表示一种判断或者可能:是不是、会不会、要不要。
注:这里你会问了,为什么前面说了that whether if,讲了前两个,独独没讲if?因此才这里单独注明。我们要注意到if和whether的词性是不同的,whether是代名词,本身就具备放在句首做主语的能力,而if是连词,是一种虚词,脱离了句子不具有完整的意思,所以我们在用if引导主语从句时,一般用形式主语。
如it is uncertain if he will leave for Beijing tomorrow.(他明天去不去北京(是)还不确定(的)。)
(2)用连接代词引导的主语从句
在由连接代词who, whose, whom, which, what, whoever, whomever, whichever, whatever引导的名词性从句中,其连接代词在句中起名词性作用,担当一定成分.
例如:What you need is more practice.
Whatever we do is to serve the people.
注:whatever / whoever的功用
whatever, whoever在主语从句中不含疑问意义。它引导主语从句,并在从句中作主语、宾语、表语等。
whatever = anything that; whoever = anyone who。要注意和whatever, whoever引导的让步状语从句的区别。
如:Whoever breaks the law should be punished. (主语从句)
(=Anyone who breaks the law should be punished. )
Whoever breaks the law, he should be punished. (让步状语从句)
(=No matter who breaks the law, he should be punished. )
这个就同我们汉语例子中的③句一样,唯一不同的是英语的区分比汉语更加明显。
(3)用连接副词when, where, why, how引导的名词性从句(其连接副词有含义,在句中作状语。)
例如:Where we should leave it is a problem.
When they will come hasn’t been made pubic.
这个就同我们汉语例子中的④句一样。
高级:it 作形式主语的主语从句(就只是为了使句子看起来更美观,调整了句子的顺序而已。)
有时为了考虑句子平衡,通常在主语从句处使用形式主语it,而将真正的主语从句移至句末。这分四种情况:
(1)对于以连词that引导的主语从句,通常用形式主语it替代主语从句:
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。
It is a mystery to me how it all happened.
It is common knowledge that the whale is not a fish.
It is no surprise that Bob should have won the game.
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.
It is doubtful whether she will be able to come.
It is essential that he should be here by the weekend.
It seems obvious that we can not go on like this.
It is necessary that you (should)master the computer.
需要注意的是这类主语从句中,谓语动词很多为“(should)+动词原形”,即要用虚拟语气。
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 used to be thought that a new star must be due to a collision between two stars.
It has not been made clear when the new road is to be opened to traffic.
It makes no difference whether he will attend the meeting or not.
It does not matter if I missed my train.
It happened that I saw him yesterday.
(2)对于以连接代词(副词)引导的主语从句,可以使用形式主语代主语从句,也可直接在句首使用主语从句:Whether they would support us was a problem. 他们是否会支持我们还是一个问题。
It was a problem whether they would support us.他们是否会支持我们还是一个问题。
(3)对关系代词型what引导的主语从句,通常直接将主语从句放在句首。如: