同学们在考研语法学习中经常容易混淆同位语从句和定语从句，对两种从句的混淆有时会直接影响到阅读文章的准确理解及翻译句子正确翻译方法的采用，以下对两种从句的区分方法进行专项总结，以便同学们轻松掌握。两种从句的区别主要在以下三方面:

1. 从词类上区别

同位语从句前面的名词只能是idea, fact, news, hope, belief, suggestion, proposal, word, thought, doubt, truth, possibility, promise, order等有一定内涵的名词，而定语从句的先行词可以是名词、代词，主句的一部分或是整个主句，如:

The possibility that the majority of the labor force will work at home is often discussed.人们经常讨论大多数劳动力将会在家里工作的可能性。(同位语从句)

Our team has won the game, which made us very happy. 我们的队赢了,这让我们很高兴。(定语从句)

2. 从性质上区别

定语从句是从句对其先行词的修饰或限制,属于形容词性从句的范畴;而同位语从句是从句对前面抽象名词的进一步的说明和解释,属于名词性从句的范畴，如:今年考研时间

The news that our team has won the game was true. 我们队赢了那场比赛的消息是真的。(同位语从句,补充说明news到底是一个什么消息。)

The news that he told me yesterday was true. 昨天他告诉我的那个消息是真的。(定语从句,news在从句中作told的宾语。)

3. 从引导词及其在句子中的成分上区别

有些引导词如how, whether, what可以引导同位语从句,但不能引导定语从句，如:

That question whether we need it has not been considered. 我们是否需要它这个问题还没有考虑。(同位语从句)

引导词that引导定语从句时,在从句中一般做主语或宾语(指物时还可以用which代替),并且作宾语时常常省略，that在同位语从句中仅起连接作用,不充当任何成分,并且不能省略,也不能用which来代替，如:

The order that we should send a few people to help the other groups was received yesterday. 我们应派几个人去帮别的几个小组的命令昨天收到了。(同位语从句,是对order的具体解释,that虽不作成分,但不能省略。)

The order that we received yesterday was that we should send a few people to help the other groups. 我们昨天收到的命令是我们应该派几个人去帮助别的几个小组。(定语从句,是名词order的修饰语,that在从句中作received的宾语,可以省略。)