主语从句学习指要
用来作主语的句子叫做主语从句。如:
(1)When he was born is unknown. 他生于何时还不知道。
(2)What he did last night is being investigated. 他昨天晚上干了些什么正在调查之中。
在主语从句中须注意:
1. 主语从句一般用it作形式主语,放在句首,而将主语从句放到句末。如:
(1)It is possible that he has stolen the car. 很可能他偷了小车。
(2)Isn’t it strange that he should not have passed the test? 他测试没有通过,难道不奇怪吗?
2. if引导主语从句时,只能用it作形式主语,放在句首,而将if引导的主语从句放到句末。如:
It is uncertain if he will leave for Beijing tomorrow. 明天他是否去北京还不敢肯定。
3. that引导主语从句放在句首时,that不可省,但在句末口语中可省。如:
That he was ill yesterday is known now. 大家都已知道他昨天生了病。
4. 连接代词引导主语从句只能放在句首。如;
(1)Who has broken the glass is unknown. 谁打破了玻璃现在还不知道。
(2)What he wants is all here. 他所要的东西都在这里。
5. 主语从句中主句的谓语动词一般用第三人称单数形式,但what引导主语从句的主句谓语动词的形式须根据句子的意思来判断。如:
(1)How he worked it out is still a secret. 他是如何把它做出来的还是一个秘密
(2)What they makes in this factory are TV sets. 他们在工厂里所做的东西就是电视机。