在句子中充当表语的从句称为表语从句。 表语从句与其它名词性从句一样,语序上采用陈述语序。 表语从语通常位于系动词be之后,其他一些系动词如 look, seem, taste, act, feel, sound 等也可以有表语从句。引导表语从句的词可以是连接词 that, as, as if/though, because, just as, like, whether; 连接代词 what, which, who, whom, whose; 连接副词 when, where, why 和 how。

1) 由 that 引导的表语从句 (that 有时可以省略)。
The problem is that most of the students think their uniforms are ugly. 问题是大部分学生认为他们的校服很难看。
The trouble was that the enemy destroyed all the bridges. 麻烦的是敌人炸毁了所有的桥梁。

2) 由连接代词引导的表语从句。
That's not what I want. 这不是我所要的。
The question is which experiment we should do first. 问题是我们应该先做哪一个实验。

3) 由连接副词引导的表语从句。
This is where our basic interest lies. 这就是我们的根本利益所在。
That is why we decided to postponed the meeting.  这是我们决定延期会议的原因。

4) 由 because 引导的表语从句。
This is because the moon is traveling round the earth. 这是因为月球绕着太阳转。
The reason I am here is because I want to talk to you. 我来这儿是想和你谈谈。

5) 由 whether 引导的表语从句。
The question is whether the food and clothes can be delivered to them in time. 问题是食物和衣服是否能被及时送到他们手里。
The point is whether this is the best way. 问题的关键是这是否是最好的方法。

6) 由 like 引导的表语从句。
He acts like he is a professional. 他装成好像是一名专家
I felt like I was sitting in an ice house. 他感到我好像就坐在一个冰屋里。

7) 由 as if/as though 引导的表语从句。
It seemed as if the world was at an end! 好像到了世界末日。
It looked as though it was going to rain. 看起来好像要下雨了。

8) 由 as/just as 引导的表语从句。
Things are not always as they seem to be. 事情并不总像表面上看来的那样。
It may be just as we think.  此事可能就像我们想的那样。