表语从句
1、表语从句概述
表语从句在复合句中作主语的表语。一般放在主句的谓语动词(联系动词)之后，引导表语从句的词有连词that, whether, as if;代词who, what, which;副词when, where, how, why等，如：
The trouble is that she has lost his address. 麻烦在于她弄丢了他的地址。
The question is whether it is worth doing. 问题在于是否值得做。
It looked as if it was going to snow. 看起来似乎要下雪。
That is what he is worried about. 那就是他所担忧的。
That is where he was born.那儿是他出生的地方。
This is how she did it. 这就是他如何做这件事的。
That is why he was late. 那便是他为何迟到了。
2、that引导的表语从句
当表语从句为陈述句的语气时，用that来引导，that无任何义，不充当任何句子成分，如：
The fact is that the child is lying. 事实是那个小孩在说谎。
The trouble is that we are short of money. 问题在于我们缺钱。
The reason is that we can’t get there on time. 原因在于我们不能按时到达那里。
3、whether引导的表语从句
当表语从句为不确定的语气时，用whether来引导，此时通常不可用if代替whether，如：
The question is whether people will buy it. 问题在于人们是否会买它。
What I want to know is whether I should to there. 我想要知道的是我是否应该去那里。
4、wh-疑问词引导的表语从句
当表语从句为疑问的语气时，用wh-疑问句来引导，要注意表语从句的语序要用陈述句的语序，如：
The question is where we should go. 问题是我们应该去哪儿。
That is why he was late. 那是他为什么迟到了
5、as if/ though引导的表语从句
He looks as if he were angry. 他看起来似乎非常生气。
同位语从句
1、用作同位语的从句，叫同位语从句。它一般跟在某些名词的后面，用以说明或解释前面的名词，引导同位语从句的词有连词that，连接副词how, when, where等，如：
I have no idea when he will be back. 我不知道他何时会回来。
We heard the news that our team had won. 我听到了我们队胜利的消息。
2、that引导的同位语从句
在某些名词后可用that引导同位语从句，如：
I had no idea that you were here. 我不知道你在这里。
The act that he won the first prize can’t be denied. 他取得第一名的事实不容否认。
3、no idea+ wh-疑问词引导的同位语从句
I have no idea where he has gone. 我不知道他去了哪里。
She had no idea how she should do. 她不知道她应该怎样做。
4、应注意的几个问题
(1)名词demand ,proposal ,suggestion等后的同位语从句要用虚拟语气，谓语为“should+动词原形“或只用动词原形，如：
The suggestion that the plan (should) be delayed will be discussed tomorrow.
推迟那项计划的建议将在明天讨论。
She refused the demand that he (should) do the work alone.
她拒绝了他单独做那项工作的请求。
(2)同位语从句与定语从句的区别
同位语从句引导词无意义，不充当成分，但不可省略，同位语从句与其说明的名词或代词应为同一内容，但定语从句的引导词要在句中作成分，是对先行词的一个限定说明，如：
He told me the news that our team won.(that引导同位语从句)
He told me the news that(which) was very exciting.(that引导定语从句)
We are interested in the news that some foreigners will visit our school.(同位语从句)
We are interested in the news that he told us.(定语从句)
