主语从句(subjectclauses)用法讲解.doc

主语从句(subject clauses)
1、概述
在复合句中起主语作用的从句叫主语从句。引导主语从句的词有从属连词、、关系代词、连接副词等。引导主语从句的关联词有从属连词that、whether，关系代词：who, what, which , whom, whose, whatever, whoever, whomever, whichever；关系副词：when, where, how, why, however, whenever, wherever等。
That you don’t like him is none of my business.你不喜欢她不管我的事。
What he said is true. 他说的是真的。
Do you remember how he arrived almost at the end of the party? 你记得他几乎是在宴会快结束时才到的吗？
This party's really where it's at, man! 啊，这个晚会真棒！
Tell us how you fulfilled the heavy task ahead of schedule.告诉我们,你们是怎样提前完成这一艰巨任务的。
We have reason to believe that the fighting on the border may develop into a full-blown war. (喻)我们有理由相信边境上的冲突可能发展成一场全面战争。
He said that he would come. 他说他要来。
Whether the football game will be played depends on the weather.足球比赛是否举行将视天气而定。
2、从属连词that，whether引导的主语从句。
从属连词that，whether在主语从句中的作用只是引导主语从句，它们在从句中不担任成分，不能省略。
Whether she will come or not is still a question. 她是否会来仍是一个问题。
That they will go is certain.他们去是肯定的。
Whether she's coming or not doesn't matter too much.她来不来没有多大关系。
3、it作形式主语引导主语从句。
如果主语从句太长，为避免句子结构头重脚轻，我们可用it作形式主语，而把主语从句放在主句谓语部分之后。That引导的主语从句可用it代替，that 不可省略。
   用作it作形式主语的结构：
（1）It is/was +形容词+that 从句
 It’s natural that…    很自然……      It’s obvious that … 显而易见……
 It’s fortunate that … 幸运的是         It’s (im)possible…（不）可能……
 It’s unlikely that… 不可能           It’s strange that…奇怪的是……
（2）It is/was +名词+that 从句
 It’s a pity that…   遗憾的是……      It’s a fact that …事实是……
 It’s good news that…是好消息……      It’s a wonder that…不足为奇……
 It’s an honour that… 非常荣幸……     It’s a shame that…真是可耻……
 It’s common knowledge that … 是常识…
（3）It +不及物动词+that 从句
 It seems that… 似乎……                It happened that…碰巧……
 It appears that…看来……               It turns out that…结果……
（4）It is/was +过去分词+that 从句
 It’s not known that… ……不得而知     It’s said that… 据说……
 It’s reported that… 据报道……        It’s decided that…尚未决定
 It’s believed that… 据认为……        It’s announced that…据宣布……
 It suddenly struck me (occur to me that… 我突然想到（感觉到）……
（5）其他
 It doesn’t matter … 是无关紧要的
 It makes no difference …毫无区别……
 It is of little consequence that…无关紧要
It is a pity that she has made such a mistake. 她犯这样的错误是令人遗憾的事。
It's strange that he didn't come yesterday. 他昨天没来是很奇怪的。
It is reported that the number of wild animals in Africa is decreasing.据报导非洲野生动物的数量正在减少。
It is said that there was a terrible plane crash this morning.据说今天早上有一起可怕的飞机坠毁事故。
3、由关系代词引导的主语从句。
（1）关系代词who, what, which, whom, whose, whatever, whoever, whomever, whichever等，引导主语从句时，它们分别在从句中担任主语、宾语或定语，不能省略。
Whoever leaves the room last ought to turn off the lights.走得最晚的应当关灯。
What you have done might do harm to other people. 你的行为可能伤害别人。
What he said at the meeting astonished everybody present.他在会议上的发言时所有入会者吃惊。
Who made the long distance call is not important.谁打的长途电话并不重要。
（2）what引导主语从句“……的东西/事情”时，可用来表示the thing(s)which这种意思，引导从句，表示一样东西与一件事情，这种用法的what称为关系代词型what，who，whom，which，what可以和ever构成合成词，和what一样引导从句，ever起强调作用。这些关系词在句子中充当成分，所以不能省略。此类主语从句不能用形式主语it引导。
What I need (=The thing which I need) is a mobile phone.我所需要的是一部移动电话。
Whoever leaves the office (=Any one who leaves the office)should tell me.无论是谁离开办公室都应该告诉我。
4、关系副词引导的主语从句。
连接副词有when, where, why, how, however, whenever, wherever等引导主语从句时，它们在从句中担任状语，不能省略。此类主语从句可以转换为以it作形式主语的句子。
Why he didn't come here is not clear to anyone.他为什么没来谁也不清楚。
How a telephone works is a question which not everyone can answer. 电话是怎样工作的，这个问题并不是每个人都能回答。
Where she has gone is not known yet.她去了哪儿，还不知道。
When they will start has not been decided yet. 他们何时动身还未定下来。
Why he did it didn't concern me. 他为什么做这件事与我无关。
5、主语从句不可位于句首的四种情况。
（1）含主语从句的复合句是疑问句、感叹句时，主语从句不可提前，用引导词it作形式主语。
Is it really true that he has gone abroad? 他真的出国了吗？
How surprising it was that he failed in the exam!真令人惊奇，他考试没有及格！
（2）It is said, reported, …结构中的主语从句不可提前。
 It’s said that the play is very interesting.据说戏剧很有趣。
 It’s reported that the highway will be opened to traffic next week.据报道，高速路下周通车。
（3）It happens, occurs…结构中的主语从句不可提前。
 It occurred to her that she had forgotten to lock the door.她突然想起忘了锁门。
It happened that I met him in the street.我恰巧在大街上遇到了他。
（4）It doesn’t matter how, whether or not…结构中的主语从句不可提前。
 It doesn’t matter whether he likes it or not.他喜欢与否无关紧要。
 It doesn’t matter how he will come.他怎么来不重要。
 6、it作形式主语与it引导强调句的比较。
       it作形式主语代替主语从句，主要是为了平衡句子结构（特别是谓语较短时），主语从句的连词没有变化。而it引导强调句则是对某一句子成分的强调（这一成分可以是词、词组或句子），其结构是“It is(was)+ 强调成分+that”。无论强调什么成分，都要求用连接词that(强调人时可以用who代替)。
 It is certain that she will succeed.她会成功是肯定的。（主语从句）
 It is in New York that I met him.是在纽约我见到了他。（强调句）