几种从句的区别
一、定语从句与表语从句
1．Is the factory where he worked near your school？他工作过的工厂靠近你学校吗？
2．Is the factory the one where he worked？这就是他工作过的工厂吗？
3．Is the factory where he worked？这工厂就是他工作过的地方吗？
析：这三个句子结构相似，均是主系表结构。若先将疑问句变为陈述句，再判断其从句的功能有助于理解。上述例句分别可变为：1）The factorywhere he worked is near our school．2）The factory is the one where he worked．3）The factory is where he worked．显然句1、2中的从句为定语从句，句3中的从句为表语从句。
二、同位语从句与定语从句
1．The news that they had won the match inspired us greatly．他们赢得了比赛的消息极大地鼓舞了我们。
2．The news that they told us yesterday proved true．他们昨天告诉我们的消息结果证明是真的。
析：判断that从句是定语从句还是同位语从句，方法是去掉that后，从句结构完整的，是同位语从句，不完整的是定语从句。如句1，去掉that，从句为they had won the match，结构完整，所以句1中的从句为同位语从句；句2，去掉that，从句为they told us yesterday，缺少直接宾语，结构不完整，所以句5中的从句为定语从句。
三、定语从句与结果状语从句
1．It is so big a stone that no one can lift it．石头太大，没有人能搬起来。
2．It is so big a stone as no one can lift．那是没人能搬起来的大石头。
3．He made such rapid progress that before long he began to write articles inEnglish．他进步很快，不久就开始用英语写文章了。
4．They talked about such things as I didn't understand．他们谈论一些我不懂的事情。
5．I want to buy the same dictionary as you have．我想买你的那种词典。
析：so／such…that中的that是从属连词，引导结果状语从句，如句1、3；而so／such／the same…as均是固定搭配，其中as是关系代词，引导定语从句，如句2、4、5。另外so…as也可引导方式状语从句，如He's not so bright as hissister（is）．
四、强调结构与主语从句（it为形式主语）
1．It was the cat's eyes that he had seen in the darkness．他在黑暗中看见的是猫的眼睛。
2．It's very clear that he's didn't understand us．非常清楚，他没听懂我们的意思。
五、what从句与that从句
1．What he told me is really true．他所告诉我的确实是真的。
＝The thing that he told me is really true．
2．They are just what I want．这些正是我所想要的。
＝They are just the things that I want．
3．We'll use what we have to get a new dress for you．我们要倾其所有为你买一件新衣服。
＝We'll use all that we have to get a new dress for you．
析：what引导名词性从句时，它既在主句中作成分，又在从句中作成分，意义上相当于the thing（s）that，all that等，可引导主语从句、表语从句和宾语从句，如句1、2、3。而that引导名词性从句时，不作任何成分（that引导定语从句除外）。另外，虽然what不引导定语从句，但以what引导的其他名词性从句，大都可改写为定语从句，如上述三例句。
