第1个回答 2017-11-12
区别：
1、主语从句(Subject Clause)
一个句子在复合句中充当一个主语,那么这个句子就是主语从句.
1）常规主语从句，句子在复合句中充当主语
That he finished writing the composition in such a short time surprised us all.
Whether we will go for an outing tomorrow remains unknown.
（1)引导主语从句连词有that,whether,who,what,whatever等
（2)连词位于句首不能省略
（3)主语从句大多数情况下视为三人称单数。
注意：为了防止句子头重脚轻，通常把形式主语it放在主语位置，真正主语搁置于句末
It seems that he has seen the film.(=He seems to have seen the film)
It happened that the two cheats were there. (=The two cheats happened to be there)
小结:
（1)以that 引出的主语从句,常以形式主语it引导. It is +形容词/名词/某些动词ed + that 从句.
（2) 在有些that从句中要用虚拟语气 (should+do/should+have done)
2、表语从句
表语从句就是用一个句子作为表语。
The problem is puzzling.
主语 连系动词 形容词作表语
The problem is when we can get a pay rise.
主语 连系动词 一个句子作表语---表语从句
连接表语从句的连接词有：that, what, who, when, where, which, why, whether,how.
He has become a teacher.
He has become what he wanted to be ten years ago.
注意：
1）一定要用陈述语序。
False: The question is when can he arrive at the hotel.
Right: The question is when he can arrive at the hotel.
2）以用if，而用whether 连接表语从句(as if 例外）。
False: The question is if the enemy is marching towards us.
Right: The question is whether the enemy is marching towards us.
Right: It looked as if he had understood this question.
3）像宾语从句，在有表语从句的复合句中，主句时态和从句时态可以不一致。
Right: The question is who will travel with me to Beijing tomorrow.
Right: The question is why he cried yesterday.
4）that 在表语从句中不能省掉。
3、 宾语从句
在句子中起宾语作用的从句叫做宾语从句.构成:带有宾语从句的复合句就是用连接词把一个主句和一个宾语从句连接在一起。
连接词有：that(可省略)，what, who, when, where, why, which, if, whether, how.
He suggested (that) we should clean the corridor every day.
Could you please tell me how you read the new book?
注意：
1）用形式宾语it代替的宾语从句
①动词find,feel,consider,make,believe等后面有宾语补足语的时候,则需要用it做形式宾语而将that宾语从句后置.
I think it necessary that we take plenty of hot water every day .
We all find it important that we (should) make a quick decision about this mater.
②有些动词带宾语从句时寻要在宾语与从句前加it
这类动词主要有:hate, take , owe, have, see to.
I hate it when they with their mouths full of food.
We take it that you will agree with us.
2）介词的宾语从句
We are talking about whether we admit students into our club.
The new book is about how Shenzhou 6 manned spaceship was sent up into space.
有时候except,but,besides三个介词后可见到that引导的宾语从句
I know nothing about my new neighbor except that he used to work with a company.
3）形容词的宾语从句
常用来引导宾语从句的形容词有: sure, ertain,glad,please,happy,sorry,afraid,satisfied,surprised
I am sure I will pass the exam.
I am sorry that I have troubled you so long.
He is glad that Li Ming went to see him when he was ill.
4. if,whether在宾语从句中的区别
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