在句子中担当主语的从句就叫做主语从句，通常放在主句谓语动词之前或由形式主语it代替，而本身放在句子末尾。通常结构为“引导词 + 主语 + 谓语 + 其他成分"。
一. 概念：在句子中担当主语的从句就叫做主语从句，通常放在主句谓语动词之前或由形式主语it代替，而本身放在句子末尾。
主语从句使用陈述语序，其通常结构为“引导词 + 主语 + 谓语 + 其他成分", 但当连接代词同时充当从句主语时，其结构为“连接代词 + 谓语 + 其他成分”。
二. 引导词：
1. that引导
eg. That you are coming to London is the best news I have heard this long time.
2. whether引导
eg. Whether they would come to conference was a question.
3. 连接代词引导: who,whom, whose, what, which, whoever, whomever, whichever, whatever
eg. Whoever is top from wins the game when two matched players meet.
4. 连接副词引导: therefore, besides, otherwise, however, moreover, still, thus, meanwhile
eg. How this happended is not clear to anyone.
5. 关系代词型what引导
eg. What shoked me was that she never wash her own clothes.
三. 形式主语it:
1. 对关系代词型what引导的主语从句，可以使用形式主语。
eg. It is clear enough what he meant.
2. 如果句子是疑问句，则必须用带形式主语it的结构.
eg. Is it true that all of us need to to conference?
好了以上就是这次为大家带来的关于主语从句的知识点讲解，大家都学得怎么样呢？千万不要忘记之后的复习哦！