高中英语名词性从句知识系统讲解

投稿:tina作者:佚名 [我的文集]来源: 时间:2016-04-23 15:27:22 阅读:89

   所谓名词性从句,就是指其作用相当于名词的从句,它包括主语从句、表语从句、宾语从句和同位语从句。

  一、主语从句

  1. 引导词:主语从句就是在复合句中用作主语的从句,引导主语从句的引导词主要有三类:一是that;二是whether;三是那些可以用作疑问词的词语,如what, who, which, when, where, how, why等。如:

  That we shall be late is certain. 我们要晚了,这是确定无疑的。

  What he says is not important. 他说的话并不重要。

  How this happened is not clear to anyone. 这件事怎样发生的,谁也不清楚。

  Which side wins makes no difference to him. 哪边赢他都无所谓。

  Whether it will do us harm remains to be seen. 是否对我们有害还要看一看。

  2. 形式主语:有时为了避免句子显得“头重脚轻”,可用it作形式主语放在句首,而把真正的主语放在句末。如:

  It’s a pity that he didn’t come. 很遗憾他没来。

  It’s not yet known what she did. 她做什么还不得而知。

  It was uncertain whether he could come or not. 他是否会来还不肯定。

  这三句句首的it均为形式主语,相应的真主语分别是that he didn’t come / what she did / whether he could come or not。

  二、表语从句

  表语从句就是在复合句中用作表语的从句。一般说来,可用于引导主语从句的引导词也可用于引导表语从句,如that, what, who, which, when, where, how, why, whether等。如:

  My idea is that we should do it right away. 我的意见是马上就干。

  That is what he meant. 这就是他的意思。

  The problem is how we can find him. 问题是我们如何找到他。

  The morning is when I’m busiest. 早上是我最忙的时候。

  That’s where you are wrong. 这就是你不对的地方。

  That’s why he didn’t come. 这就是他没有来的缘故。

  另外,表语从句还可以用as if, as though, because等来引导。如:

  It is because he is too foolish. 那是因为他太蠢了。

  It is not as though we were poor. 又不是我们家里穷。

  三、宾语从句

  1. 引导词:宾语从句就是在复合句中用作宾语的从句。一般说来,可用于引导主语从句的引导词也可用于引导宾语从句,如that, what, who, which, when, where, how, why, whether等。如:

  We believe that he is honest. 我们相信他是诚实的。

  She has got what she wanted. 她要的东西得到了。

  I haven’t decided whether I should go. 我还没决定我是否会去。

  I asked how he was getting on. 我问他情况怎样。

  He asked when the train would get in. 他问火车什么时候进站。

  He asked me where I was going. 他问我到哪儿去。

  Please tell me which you like. 告诉我你喜欢哪一个。

  He asked who lived next door. 他问谁住在隔壁。

  She asked why he was silent. 她问他为什么一言不发。

  2. if与whether:两者均可用于及物动词后引导宾语从句,表示“是否”,常可互换。但除此(用于动词后引导宾语从句)之外,在其他情况下表示“是否”时,通常要用whether 而不用if,如用于引导主语从句、表语从句、同位语从句、让步状语从句、与or连用分别引导两个分句等,或用于不定式前、用于介词后、直接与or not 连用等等。如:

  Ask him whether [if] he can come. 问他能不能来。

  The question is whether he can do it. 问题是他能不能做。

  Answer my question whether you can help him. 回答我你是否能帮助他。

  It depends on whether the letter arrives in time. 这取决于信是否来得及时。

  注:在某些动词后(如discuss 等) 通常只用whether。如:

  We discussed whether we should hold a meeting. 我们讨论了是否要开一个会。如:

  I wonder if it’s large enough. 不知它是否够大。

  She didn’t say if he was still alive. 她没说他是否还活着。

  但是,当于用于介词后引导宾语从句时,只能用whether,不能用if。如:

  I worry about whether I hurt her feelings. 我为是否伤了她的感情而忧虑。

  3. that的省略:that引导主语从句或表语从句时通常不省略,但引导宾语从句时通常可以省略。如:

  She said (that) she didn’t want to know. 她说她不想知道。

  I don’t think (that) she’s interested in it. 我想她对这事没有兴趣。

  4. 否定转移:当主句主语为第一人称,且主句谓语动词为think, believe, suppose, expect, imagine等时,若其后接一个表示否定意义的宾语从句,此时通常应将否定转移到主句上。如:

  I don’t think that he will leave. 我认为他不会离开。

  I don’t believe that it is easy. 我相信这不会容易。

  2. if与whether:if通常不用于引导主语从句或表语从句,但可以用于引导宾语从句,与whether用法相同,常可互换。如:

  I wonder if it’s large enough. 不知它是否够大。

  She didn’t say if he was still alive. 她没说他是否还活着。

  但是,当于用于介词后引导宾语从句时,只能用whether,不能用if。如:

  I worry about whether I hurt her feelings. 我为是否伤了她的感情而忧虑。

  3. that的省略:that引导主语从句或表语从句时通常不省略,但引导宾语从句时通常可以省略。如:

  She said (that) she didn’t want to know. 她说她不想知道。

  I don’t think (that) she’s interested in it. 我想她对这事没有兴趣。

  4. 否定转移:当主句主语为第一人称,且主句谓语动词为think, believe, suppose, expect, imagine等时,若其后接一个表示否定意义的宾语从句,此时通常应将否定转移到主句上。如:

  I don’t think that he will leave. 我认为他不会离开。

  I don’t believe that it is easy. 我相信这不会容易。

  四、同位语从句

  在复合句中用作同位语的从句叫同位语从句。所谓同位语,就是指两个语法单位指同一个人或事物,并且句法功能也一样,此时我们就把后一项称为前一项的同位语。所谓同位语从句,就是指用于名词后对该名词的内容进行说明解释的从句。如:

  The judge paid no attention to the fact that she had just lost her husband. 法官毫不考虑她刚刚失去丈夫一事。

  句中的that she had just lost her husband为修饰名词the fact的同位语从句,用以具体说明the fact的内容。

  Mary suddenly got the feeling that someone was watching her. 玛丽突然感到有人在看她。

  句中的that someone was watching her为修饰名词the feeling的同位语从句,用以具体说明the feeling的内容。

  英语中只有少数名词可后接同位语从句,比较常见的有belief, doubt, fact, feeling, hope, idea, message, news, opinion等。

  另外,同位语从句的引导词也比较有限,主要是由that引导,有时可也可用when, how, where, whether, who等引导,但是不能用if也引导,也不能用what来引导。如:

  You have no idea how worried I was! 你不知道我多着急!

  He had no idea why she left. 他不知道她为什么离开。

  There is some doubt whether he will come. 他是否会来还不一定。