全力直击英语语法:名词性从句
文章作者 100test 发表时间 2007:02:24 19:59:11
来源 100Test.Com百考试题网
名词性从句是由if, whether, that 和各种疑问词充当连接词所引导的从句,其功同名词一样。
一.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
It 作形式主语代替主语从句,主要是为了平衡句子结构,主语从句的连接词没有变化。而it引导的强调句则是对句子某一部分进行强调,无论强调的是什么成分,都可用连词that。被强调部分指人是也可用who/whom。例如:
It is a pity that you didn t go to see the film.
It doesn t interest me whether you succeed or not.
It is in the morning that the murder took place.
It is John that broke the window.
2. 用it 作形式主语的结构
(1) It is +名词+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+从句
It is natural that…很自然…
It is strange that…奇怪的是…
(3) it is +不及物动词+从句
It seems that…似乎…
It happened that…碰巧…
(4) it +过去分词+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. (right)
That President Jiang will visit our school next week is said. (wrong)
(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. (right)
That he failed in the examination occurred to him. (wrong)
(4) It doesn t matter how/whether …结构中的主语从句不可提前。例如:
It doesn t matter whether he is wrong or not. (right)
Whether he is wrong or not doesn t matter. (wrong)
(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? (right)
Is that will rain in the evening likely? (wrong)
4. What 与that 在引导主语从句时的区别
What 引导主语从句时在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:
1) What you said yesterday is right.
2) That she is still alive is a consolation.