同位语与定语从句的区别

同位语从句和定语从句的区别
什么是同位语从句：
在某些名词后面（如idea,news, hope, belief, thought, doubt等）可以用that或者其他连接词引起从句，用来解释前面名词的具体内容，这叫做同位语从句。
I have no idea where she left the bag.
We expressed the hope that we would visit China again.
I’ve come from Mr. Lin with a message that he won’t be able to see you this afternoon.
Have you any proof that he is a thief?
The news that we are having a holiday tomorrow is not true.
There can be no doubt that he is fit for the job.
Then came the question where we were to get the machines we needed.
The thought occurred to him that maybe the enemy had escaped.
The question whether he will come or not is not settled.
同位语从句和定语从句的几点区别
1.同位语从句的先行词多数为抽象名词，比如idea, thought, question, hope , belief, truth, news, fact, doubt, message, order, chance, possiblity, proof, 等等。而定语从句的先行词可以是很多n.或代词，有人，有物，有时间，有地点，有原因，抽象名词也可以成为定语从句的先行词。
2.同位语从句能够解释先行词的具体内容，属于同等位置关系，而定语从句只能对先行词起到限定修饰作用，不能解释清楚其具体内容。如：
The news that he succeeded in the test made us happy.
The news that he got from the teacher made us happy
同位语从句
定语从句
3.同位语从句多数用that引导，that无成分，无意义，仅起到连接作用。而定语从句的that可以做主语，可以作宾语（此时可省），有时还能用which替换。
The truth that he was a thief
made us surprised.
The truth that he got from the police
made us surprised.
同位语从句
定语从句
=(which)
4.同位语从句可以用whether引导，定语从句不行。whether有意义“是否”，但无成分。
The question whether he will come or not is not settled.
定语从句可以用whom, who, whose引导，而同位语从句不行，因为它的先行词是抽象名词，不是sb.
5.when，where，和why引导定语从句时，先行词必须分别是时间名词，地点名词和reason.
但他们引导同位语从句时先行词却不是这些。
I have no idea when she will be back.
I don’t know the time when she will be back.
I have no idea where she left the bag.
I don’t know the place where she left the bag.
The question why we must learn English has been asked many times.
The reason why we must learn English has been explained.
同位语从句
同位语从句
同位语从句
定语从句
定语从句
定语从句
6.同位语从句前面通常没有逗号。而定语从句有非限制性的。但要注意“同位语+定语从句”的这种句式。
Meeting my uncle after so many year

s is an exciting moment, ____ I will treasure forever.
A.one B. the one C. that D. a one
分析：one= a moment,是同位语，后面的I will treasure forever 是省略了that（做vt. treasure的宾语）的定语从句。that不能引导非限制性定语从句，a和one不可以直接连用，故C、D不对。
请看一个简单的例子：
He is a good teacher, a teacher whom we all love.
=…………………………….., one we all love