18.3 同位语从句
同位语从句是一种名词性从句，用于对其前面的名词进行进一步的说明。这些名词常见的有doubt, fact, message, proof, opinion, hope, impression, evidence, idea, belief, feeling, conclusion, rumour, report, possibility, guarantee, thought, assurance等。
1) 由that 引导的同位语从句
There was little hope that he would survive. 他幸存的希望很小。
We came to the decision that we must act at once. 我们做出决定：我们必须立即行动。
We heard the news that our team had won. 我们听到消息说我们队赢了。
He made a proposal that the meeting be postpone. 他提议会议延期。
There is no doubt that he will keep his promise. 我们相信他会守信。
They expressed the wish that she accept the award. 他们表示希望她接受这笔奖金
There is no evidence that he committed crime. 没有他犯罪的证据。
2) 由连接代副词引导的同位语从句
I have no idea when he will be back. 我不知道他什么时候会回来。
He had no idea why she left. 他不知道她为什么离开。
The question who was to blame has never been settled. 该由谁负责， 这个问题根本没有解决。
3) 由whether 引导的同位语从句
He hasn’t made the decision whether he will go there. 他还没有做出决定是否去那里。
We are not investigating the question whether he is trustworthy.
我们不是在调查他是否可以信任的问题。
I have small doubt whether he is suitable for the job. 他是否适合这件工作我有点怀疑。
4) 由 what 引导的同位语从句
I have no idea what he is doing now. 我不知道他现在在干什么。
Next comes the question what you want it for. 其次就是这个问题， 你为什么要它。
5) 同位语从句有时和前面的名词分开。
The news got about that the firm was closing down. 消息传开说公司将要倒闭。
Report has it that the princess is getting married this year. 据说公主今年将结婚。
The rumour spread that they had been arrested. 谣传他们被逮捕了。
Word came that he had been abroad. 据说他已经出国了。
6) 同位语从句与定语从句的区别
a) 从意义上讲，同位语从句是名词性从句，用于对其前面的名词进行进一步的说明，与先行词是同位的关系；而定语从句是用来修饰先行词，是从属的关系。
b) 从结构上讲，that在同位语从句中为连词，不充当句子成分；而在定语从句中that代替先行词在从句中充当主语、宾语等句子成分。
c) 有些引导词如whether, what, how等可以用来引导同位语从句，但它们不能用来引导定语从句。
d) 可作同位语从句的先行词的名词比较有限，常见的有doubt, fact, message, proof, opinion, hope, impression, evidence, idea, belief, feeling, conclusion, rumour, report, possibility, guarantee, thought, assurance等。而定语从句的先行词则比较广泛，包括大部分名词及代词。
