1、引导主语从句的连接词有从属连词that, weather, 连接代词who, what, which等等，咒邃狁廖连接副词when, where, how, why等。主语从句在句首时，必须由连接词引导，不能省略这些连接词
3、连接代词引导的主语从句，例如what seems easy to some people seems difficult to others, which side will win is not clear
5、主语从句可以前置，也可以后置，用it作形式主语时，须把主语从句放在句末，常用下面几种句型：it+be+表语（名词，形容词，过去分词）+主语从句
