职称英语考试经验：名词性从句
在句子中起名词作用的句子叫名词性从句。名词性从句的功能相当于名词词组，它能在复合句中作主语、宾语、表语、同位语等。根据它在句中不同的语法功能，名词性从句分为主语从句、宾语从句、表语从句和同位语从句。在名词性从句中，连接词that既没有实际意义，又不充当任何成分，只起引导从句的作用， 引导宾语从句时经常省去。
一、主语从句 (The Subject Clause)：在复合句中作主句的主语。为保持句子结构平衡，主语从句通常被置于句末，而用it作形式主语。
That light travels in straight line is known to all.
When the plane is to take off hasn’t been announced.
It was my fault that I had him play football yesterday afternoon.
It is important that we should go to the school to talk with the teacher.
It is still unknown which team will win the match.
二、宾语从句 (The Object Clause)：主要作及物动词的宾语，有时置于介词或形容词之后。
He said (that) his father had come back from the United States.
He asked how much I paid for the violin.
No one can be sure what man will look like in a million years.
如果宾语从句带有补足语，通常用it作形式宾语，而把宾语从句置于补足语之后。
I think it necessary that we should pay close attention to SARS.
We all feel it our duty that we should serve the people heart and soul
当主句的谓语动词是think， believe， guess， expect， imagine， suppose等时，如果宾语从句是否定结构，通常把主句谓语动词改为否定式，而将宾语从句改为肯定式，这种现象叫做“否定转移”。
I don‘t think we two have met before.
We don‘t believe that he could finish his work in such a short time.
She doesn‘t think it is right for John to come late to school.
三、表语从句 （The Predicative Clause）：通常置于主句的系动词之后，说明主句主语的情况。
My idea is that we should help her do housework every Sunday.
Is that why you had a few days off？
It is because I have never heard of the story.
四、同位语从句 （The Appositive Clause）：常置于某些名词之后，对其内容作解释或补充说明。如：
advice， demand， doubt， fact， hope， idea， news， order， problem， promise， question， request， suggestion， truth， wish， word等。
The news that we won the game is exciting.
There is no doubt that he is the best player in their country.
同位语从句与定语从句的区别：
同位语从句对所修饰词作补充说明，而定语从句对前面名词起限定作用；
that在同位语从句中只起引导作用，无词义，无语法成分，而在定语从句中指代所修饰词并在从句中作主语或宾语。
比较：The idea that one can do the work without thinking is wrong. （同位语从句）
The idea that you put forward at the meeting is wrong. （定语从句）