什么是表语从句 要详细

表语就是在系动词之后的成分。
表语从句是名词性从句的一种。
系动词主要包括，be动词，感官动词（look observe smell taste feel lisen ... ）除此以外还有，remain seem keep 等表状态的词，get turn grow 等表变化的词。不用背这些系动词，只要知道认得出来就可以了，初中主要就是前两种。

根据句易，填连接词或者连接副词，一般的连接词都可以用。像that which who whom where when why how as...

eg. The truth is that I have never been there.
It looks as if it were going to rain.

加油！