英语中名词性从句的几中区别方法

http://news.hongen.com/news/show_34_62.html
http://www.google.cn/search?client=aff-os-maxthon&forid=1&ie=utf-8&oe=utf-8&hl=zh-CN&q=%E5%90%8D%E8%AF%8D%E6%80%A7%E4%BB%8E%E5%8F%A5

主语从句、表语从句、宾语从句、同位语从句在复合句中起名词的作用，这四种从句合称名词性从句。它们在主句中充当主语、表语、宾语或同位语，都不能用逗号与主句分开。(注：句中划线部分为从句)

■主语从句

1、定义：先找到句子的谓语，主句的谓语前面的从句，叫做主语从句。

Why he left wasn't important.(wasn't是主句的谓语动词，why he left做主语从句)

That she became an artist may have been due to her father's influence.(may have been due是主句的谓语动词，that she became an artist做主语从句)

2、借助形式主语it，主语从句放在后面

①由that引导的主语从句可以放在主语的位置，这时that不可以省略。例如：That prices will go up is certain.

that主语从句放在句首的情况不是很常