解题思路： 首先要清楚句子的成分：主系表， 主谓宾。系动词的后面是表语。
解题过程：
表语从句：
1．定义：用作表语的从句叫做表语从句。
2．构成：关联词+简单句
3．引导表语从句的关联词的种类：
(1) 从属连词that。如：
The trouble is that I have lost his address. 麻烦是我把他的地址丢了。
(2) 从属连词whether, as, as if。如：
He looked just as he had looked ten years before. 他看起来还与十年前一样。
The question is whether they will be able to help us. 问题是他们是否能帮我们。
注：从属连词if一般不用来引导表语从句，但as if却可引导表语从句。
All this was over twenty years ago, but it”s as if it was only yesterday.
这都是20多年前的事了，但宛如昨天一样。
能跟表语从句的谓语动词一般为系动词be, seem, look等。如：
It looked as if it was going to rain. 看起来天要下雨了。
(3)连接代词who, whom, whose, what, which, whoever, whatever, whichever
连接副词 where, when, how, why。
The problem is who we can get to replace her. 问题是我们能找到谁去替换她呢。
The question is how he did it. 问题是他是如何做此事的。
宾语从句：是做动词、介词或形容词宾语的从句。
一、做动词的宾语：
I think (that) you will like the pictures.我想你会喜欢这些画的。
（连接词that无意义，在从句中不充当任何成分，可以省略）
当宾语从句（通常是由that引导的宾语从句）有一宾语补足语时，常用it作形式宾语，而将宾语从句置于句末。例如：
I feel it important that they finish their own task in time. 我觉得他们按时完成自己的任务是很重要的。
二、做介词宾语：
They are worrying about whether they can get there in time. 他们正担心是否能及时赶到那里。
You can write about whatever topic you can think of. 你可以写一写你能够想到的任何话题。
三、做形容词宾语：
Are you sure what you will do next? 你确信接下来你会做什么吗？
I”m afraid that he will fail in the exam. 恐怕他会考试不及格。
表语从句只能接在系动词后面。
