名词性从句

　　在复合句中起名词作用的从句叫做名词性从句。根据它在句中不同的语法功能，名词性从句又可分为主语从句、表语从句、宾语从句和同位语从句。引导名词性从句的引导词有whether, if, that, who, what, which, when, where, how, why等。

【归纳】

一、主语从句

★用作主语的从句叫做主语从句。如：

That she became an artist may have been due to her father's influence.

What hurt my feelings was Gina's comment.

How the prisoner escaped is a complete myster.

★有时可用形式主语it代替主语从句，即将it放在句首，将主语从句放在句末，以免句子头重脚轻。如：

It is strange that Martha knows nothing about it.

It is doubtful whether he is coming.

★that引导主语从句时，在句中无实际意义，不充当句子成分，只起连接作用。当它引导的主语从句置于句首时，that不能省略；如果用it作形式主语，把主语从句放在句末时， that可以省略。如：

That we shall be late is certain.

It is a pity (that) Susan can't swim.