英语高手请进

Question

主语从句、同位语从句、定语从句的区别是...？
（最好能举几个典型的例子）

Answer 1

主语从句
1.主语从句可以直接放在句首；也可用it作形式主语，而将从句放于句末。
That light travels in straight lines is known to all.
It's known to all that light travels in straight lines.

2.主语为从句时，谓语动词用单数。但如果what引导的从句作主语、代表复数概念时，谓语动词常用复数。
What we need is water.
What we need are useful books.

3.主语从句和同位语从句同属于名词性从句，区别在句子中所起的语法作用不同。

同位语从句
同位语从句跟在一个名词后面，对其作进一步解释：
I had no idea that you were here.

1.同位语从句有时被别的词把它与名词隔开：
The story goes that William Tell killed the tyrant with an arrow.

2.同位语与定语从句的区别

①.前者对名词加以补充说明，后者对名词进行修饰和限定。

②.前者有连接词that 等引导，后者由关系词who where which when等引导

③.前者说明的名词与从句没有逻辑关系，后者的名词则是从句逻辑上的主语、宾语、表语、状语。
The news that they won the match is true.(同位语从句)
The news that you told me yesterday is true.(定语从句，news 是 told 的宾语)

④.引导同位语从句的连词不可省略，而引导定语从句的关系代词作宾语是常可省略。

⑤.同位语从句说明的名词大多数为抽象名词，而定语从句没有限定。

定语从句
形容词性从句，修饰一个名词、代词，甚至一个句子。
That is the place where he works.