定语从句讲解构成1.了解定语从句的构成，首先应了解一些相关的基本概念。a.被修饰的名词等成分通常叫做先行词；b.连接先行词和定语从句的词为关系词。2.定语从句由关系代词、关系副词和关系限定词三类关系词连接而成，这三种也将在定语从句讲解中一一说明。定语从句讲解关系词的具体用法1.关系代词 which，who，whom，that 和 as2.关系代词，顾名思义，必有代替对象。上述五个关系代词各有其具体指代对象，在从句中作相应的成分。此外，它们引导的定语从句和先行词是形容词与名词的修饰关系。例句1:Pumas are large，cat-like animals( that/which are found in America.)【译文】美洲狮是体形似猫的大型动物，产于美洲。【注解】关系代词作从句主语，不可省略。例句2:The house (that/which we built last year) is very attractive.【译文】我们去年建造的房子很讨人喜欢。【注解】关系代词作从句宾语，可省略。例句3:The novel (with/which most of you are familiar) has been adapted for the screen.【译文】你们大多数都很熟悉的那部小说已被改编搬上了荧屏。 【注解】关系代词直接置于介词后作介词宾语，此时不可被that替换，也不可省略。例句4:He was no longer the reckless young man( that/which he was two years ago).【译文】他不再是两年前那个莽撞的小伙子了。 【注解】关系代词作从句表语，可省略;此外，先行词the young man代表一种状态，属物的范畴，不能用who来引导定语从句。例句5:Migrant workers(to whom much more attention has been paid) strongly desire that their wages should be duly paid.【译文】现在民工受到了社会更大的关注，他们强烈渴望自己的工资能够及时发放。 【注解】关系代词直接置于介词后作介词宾语，此时不可被who替换，也不可省略。例句6:Such accommodations（as they could find) were generally expensive.【译文】他们能够找到的这些住所费用往往比较昂贵。 【注解】之所以选择关系代词as引导定语从句，是因为前面有such之故。例句7:Such inns(as there were in the mountains) were generally poor.【译文】这些山区里的酒馆条件往往比较糟糕。【注解】之所以选择关系代词as引导定语从句，是因为前面有such之故。例句8:This is the same mosquito（as bit you just now).【译文】这只蚊子和刚才咬你的那只是同一种蚊子。【注解】之所以选择关系代词as引导定语从句，是因为前面有the same之故。定语从句讲解小结：(1)一般来讲，which和that用来替代指物的先行词，在定语从句中可作主语、宾语或表语 (that不能作介词后面的宾语）；who替代指人的先行词，在定语从句中作主语或宾语(但不能 作介词后面的宾语）；whom是who的宾格形式，替代指人的先行词，在定语从句中只能作宾 语;as作为关系代词，只能用于一些特殊搭配(such... as/the same... as)。(2)that既可指物也可指人，但在当代英语中，多指物。(3)当关系代词在限制性定语从句中作宾语或表语时，经常可省略，但当which，whom 紧跟在介词后则不可省略。例如：Is that the man(with whom you are going to set up a law firm)?Is that the man(who/whom)(you are going to set up a law firm with)?(4)只能用that的情形a.当先行词为 all,much,anything, something, nothing,everything, little,none 等不定代 词，或先行词被all，any，every等不定代词修饰时，只能用that替代指物的先行词。例如：①That'a all(that I ask for).【译文】这就是我要的一切。②Is there anything(that I can do for you) ?【译文】我可以为您效劳吗？③Every tearo（that intends to participate in the contest) is to submit a fee of 2000.【译文】每一个意欲参加比赛的队伍都应该缴纳两千元的费用。b.先行词被形容词最髙级修饰，或被the only,the first,the last,the next,the very等修饰时，只能用that替代指物的先行词。例如：①He eats the finest food(that is available).【译文】他吃的是所提供的最精美的食物。②The first case of bird flu( that was reported in Thailand) captured the attention of officials with WHO.【译文】泰闰报道的第一例禽流感引起了世界卫生组织官员们的注意。③This is the very book(that I have been hunting for a long time).【译文】这就是我长期以来一直寻找的那本书。c.先行词既包括人，又包括物时。例如：①He is always talking brilliantly of the book and author(that interested him)【译文】他对那本书及其作者很感兴趣，总是兴高采烈地谈论着他们。② We were deeply impressed by the school and its teachers (that we had visited there).【译文】我们访问的学校和老师给我们留下了深刻的印象。(5)只能用which的情形a.用于介词之后（可参见A例句3)。b.用于非限制定语从句中。以上是对于定语从句讲解中关系代词的独立讲解，更多的关于定语从句讲解知识将会陆续更新。