一、主语从句的构成：关联词＋简单句
二、引导主语从句的关联词有三类：
1．从属连词that
That they were in truth sisters was clear from the facial resemblance between them.
很明显，她们确实是亲姐妹，她们的脸型很相似。
2．从属连词whether
Whether he'll come here isn't clear.
他是否会来这里还不清楚。
3．连接代词who，whom，whose，what，which，whoever，whatever，whichever
Whoever comes is welcome.不论谁来都欢迎。
Wherever you are is my home—my only home.
你所在的任何地方就是我的家——我唯一的家。
What she did is not yet known.她干了什么尚不清楚。
