一、同位语从句与定语从句的区别
同位语从句与定于从句从形式上来看很相似，大多都是由that来引导，都跟在名词或代词后。但两者在用法和功能上还是有很多区别的。
和先行词的关系不同。对于同位语从句来说，同位语从句说明先行词的具体内容，二者是同位关系。而定语从句修饰限定先行词，二者是修饰关系。
例如：The news that he told me is that Tom would go abroad next year.这个句子中第一个that引导的从句是定语从句，that在从句中作宾语。
The news that Tom would go abroad is told by him.而这个同位语从句中，that在句子中不作任何成分。
定语从句由关系代词或是关系副词引导，关系词在从句中担当相应的句子成分，可以做主语、宾语或表语等，但作宾语时常被省略。同位语从句主要有连词that引导，在从句中不担当成分。
还有，同位语从句与定语从句的引导词也是不一样的，what, how, if, whatever 等词可以引导同位语从句，但不引导定语从句。同位语从句与先行词可以用be动词发展成为一个完整的句子，但是定语从句是不可以的。
二、定语从句经典例句长句
1. I went to visit the American author who wrote a number of books about China.
2. I ate the soup my aunt prepared.
3. I have an arrangement with my bank, by which they let me use their money and repay them next month.
4. He sent her a letter, in which he said that he was sorry for what he had done to her.
5. Mr. Brown, who just came from Britain yesterday, will teach us accounting this term.
6. She is going to spend the winter holidays in Hainan, where she has some relatives.
7. The United States is known for its supermarkets, where huge quantities of all kinds of food and household articles are sold.
8. The story happened in late 19th century, when China is suffering from the invasion of western powers.
