主语从句语法详解是什么?
“主语从句”语法详解：
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?
引导主语从句的连词概括：
（1）从属连词：that、whether。
（2）连接副词：why、when、whenever、where、wherever、how、however。
（3）连接代词：whom、whose、who、whoever、what、whatever、which、whichever。
以上内容参考：百度百科-主语从句
