判断表语从句如下：
表语从句的构成方式：若从句为陈述句，直接加that；若从句为特殊疑问句：直接保留特殊疑问词，后面的句子变成陈述句语序；若从句为一般疑问句：先把一般疑问句变成陈述句语序，然后在其前加上weather或者if；
eg：China is no longer what she used to be.
The question is who is responsible for what has happened.
拓展资料：
表语从句引导词的用法：
1. that引导的表语从句
(1) that 在从句中仅起连接作用，无实际意义，在句中不做任何成分，不能省略。
例：
My opinion is that it’s getting better and better.
(2)在表 “建议，劝说，命令” 的名词idea，suggestion，request，proposal后面的表语从句中，谓语动词用“should + 动词原形”，should可省略。
例：My suggesstion is that we (should) start early tomorrow.
2. whether 在表语从句中表“是否”，但不充当句子的成分。if不能引导表语从句。
例：The question is whether it is worth doing.
3. what 在表语从句中充当主语、宾语或表语，表示什么，什么样子，或所…的（人或事）。
例：The question is what caused the accident.
4. who 在表语从句中充当主语、宾语或表语，表示“谁”.
例：The problem is who could do the work
5. which 在引导表语从句时，常充当定语，表语。表示“哪一个，哪一些”。
例：I read about it in some book or another,but what I don’t know is which (book) it is.
6. 由as if，as though引导表语从句，表示“好像”。句子中的系动词常用be, look, appear, seem，sound等。
例：It looksas if it is going to rain.
The young man with long hair looks as if he were a girl. （虚拟语气）
7. 当主句的主语为reason，或者是由 why 引导的从句时，与它们相关的表语从句用 that 来引导，而不能由 because 引导。because 引导表语从句时只能用于It/That/This is /was because…句型中。
例：The reason why I was late was that I missed the train.
I was late. It/That/This was because I missed the train.
8. 当表语从句中主语、宾语、表语具备，但还是要表示疑问含义，可以判断句子中缺少状语，常常用相应的特殊疑问词引导，有why，when，where，how 等。
例：This is how he did it.
That is why the brothers wanted to make a bet.
That’s why we’ve given you the letter.