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。
4．连接副词 where，when，how，why
How this happened is not clear to anyone.
这事是怎样发生的，谁也不清楚。
