一、主语从句
即在复合句中充当主语成分的句子，例如"That he finished writing the composition in such a short time surprised us all"，他在很短的时间内写完作文让我们都很惊讶，此复合句主要描述的是某事让我们惊讶，某事就是该复合句的主语，因此"That he finished writing the composition in such a short time"便是该复合句的主语从句。
that引导
That he is still alive is a wonder.
他还活着，真是奇迹。
That we shall be late is certain.
我们要晚了，这是确定无疑的。
whether引导
Whether it will do us harm remains to be seen.
是否对我们有害还要看一看。
Whether they would support us was a problem.
他们是否会支持我们还是一个问题。
连接代词引导
Whoever is top from wins the game when two matched players meet.
两强相争勇者胜。
Whichever (of you) comes in first will receive a prize.
无论(你们)谁先到都可以得奖。
连接副词引导
When we arrive doesn't matter.
什么时候到没有关系。
How it was done was a mystery.
这是怎样做的是一个谜。
关系代词型what引导
What we need is money.
我们需要的是钱。
What I want to know is this.
我想知道的就是这一点。
二、宾语从句
宾语从句的连接词：that；
结构：主语+谓语+宾语（陈述句语序）、从属连词。
连接宾语从句的从属连词主要有that,if,whether，和特殊疑问词（what， how， where， when等)。that引导表示陈述句的宾语从句，if和whether，whether…or not引导表示“是否”的一般疑问句的宾语从句。
that引导
We believe that he is honest.
我们相信他是诚实的。
The doctor insists that I give up smoking.
医生坚持要我戒烟。
whether / if引导
I don’t know whether he’ll arrive in time.
我不知道他是否能及时到。
I didn’t know whether they liked the place.
我不知道他们是否喜欢这个地方。
连接代词引导
I don’t know who [whom] you mean.
我不知道你指谁。
Please tell me which you like.
告诉我你喜欢哪一个。
连接副词引导
He asked why he had to go alone.
他问他为什么必须一个人去。
You don’t know when you are lucky.
你身在福中不知福。
关系代词what引导
She has got what she wanted.
她要的东西得到了。
I want to tell you what I hear.
我想把听到的情况告诉你。
三、表语从句
表语从句(Predicative Clause)就是用一个句子作为表语。说明主语是什么或者怎么样，由名词、形容词或相当于名词或形容词的词或短语充
The reason why he was dismissed is that he was careless and irresponsible.
他被开除的原因是他粗心和不负责任。
Women are much too preoccupied with family. Once the marriage begins to disintegrate, they’re lost. That’s where their unhappiness springs from and that’s why most divorced mothers regard themselves as victims.
妇女对家庭都太过投入了。一旦婚姻瓦解，她们就什么都没了。那就是他们不开心的根源和为什么大多数离婚的母亲都认为自己是受害者的原因。
Change is what keeps us fresh and innovative. Change is what keeps us from getting stale. Change is what keeps us young.
改变使我们保持创新。改变使我们远离陈腐。改变让我们永葆青春。
This is because it is young people in our society who are able to impose changes.
这是因为我们社会中的年轻人才能带来改变。(此句子中有一个强调句)
Another reason for this is that old buildings, like native languages, form a cultural identity and keep a unique record of a country.
另一个原因是：旧建筑，就像母语一样，组成了文化特征，保存了一个国家独有的记录。