表语从句的引导词用法归纳总结

在复合句中作表语的从句叫表语从句。表语从句位于主句的系动词后。表语从句说明主语是什么，对主语进行解释、说明，使主语的内具体化。

例：

The problem is when we can get a pay rise.

问题是什么时候我们可以得到加薪。

主语+系动词+表语从句

可以接表语从句的系动词有：

be，feel，seem，look，sound，taste，smell，appear，remain，keep，stay，become，get，grow，turn，go，prove，turn out 等。

引导表语从句的引导词有：

that，what，which，who，whether，if，how，when，why，where等

例：

The book is not what I need.

The question is when he can arrive at the hotel.

Protocol(协议) was what enabled(缺主语) him make difficult decisions without ever looking back.

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.

1. that 引导表语从句时不能省。

2. if 不能引导表语从句。

3. 除 that 外的所有引导词都有自己的意义。

4. 除that，whether外的所有引导词都须在从句中充当相应的成分。