从句讲解高中英语

复合句由一个主句和一个或一个以上的从句构成。主句是全句的主体，往往可以独立存在，而从句只是全句的一个句子成分，不能独立存在。例如：We met where the roads crossed.I forgot to post the letter which I wrote yesterday.从句虽然不能单独成句，但它也有主语部分和谓语部分，从句需要由一个关联词引导。引导从句的关联词有七类。从属连接词——whether、when、 although、because、if。He will get the letter tomorrow if you send it off now.I don't know what you mean.疑问代词——who、whom、 whose、which、what。Who he is doesn't concern me.I don't know what you mean.疑问副词——when、where、why、how。I asked how he was going on.I can't understand why he was so late.关系代词——who、whom、whose、which、that。Nobody who understands the subject would say such a thing.Water that is impure often causes serious illness.关系副词——when、where、why。July and August are the months when the weather is very hot.She would like to live in a country where it never snows.缩合连接代词——what、 whatever、who、whoever、that、 whichever。Show me what you have written.Whoever does wrong is punished in the end.缩合连接副词——whenever、where、wherever、 however。Whatever he goes out, he always takes his umbrella.Sit wherever you like.从句分为主语从句、表语从句、宾语从句、同位语从句、定语从句和状语从句。由于主语从句，表语从句和宾语从句在句子里的功用相当于名词，所以叫做名词性从句。名词性从句的关联词大抵相同，而且其前一般不用逗号。