定语从句和非限制性定语从句的用法

理解的不透彻

　一、关系代词（在句中作主语、宾语或定语）

　　1. that既可代表事物也可代表人，which代表事物；它们在从句中作主语或宾语，that在从句中作宾语时常可省略关系词，which在从句中作宾语也可以省略。[eg：this is the book （which）you want。]

　　2而且，如果which在从句中作“不及物动词＋介词”的介词的宾语，注意介词不要丢掉，而且介词总是放在关系代词which的前边，但有的则放在它原来的位置

　　3. 代表物时多用which，但在带有下列词的句子中用that而不用which，这些词包括当先行词是anything, everything, nothing , none等不定代词时，或者是由every, any, all, some, no, little, few, much等修饰时等，这时的that常被省略 还有先行词前有序数词或形容词最高级修饰时,或先行词就是序数词或最高级时.以及先行词中既有人又有物时.还有句中前面有which时,都只能用that

　　4. who和whom引导的从句用来修饰人，分别作从句中的主语和宾语，whom作宾语时，要注意它可以作动词的宾语也可以作介词的宾语

　　5. whose是关系代词，修饰名词作定语，相当于所修饰成分的前置所有格.它引导的从句可以修饰人和物, 当它引导的从句修饰物体时, 可以与 of which 调换,表达的意思一样。

　　二、关系副词（在句中作状语）

　　关系副词=介词+关系代词

　　why=for which

　　where=in/ at/ on/ ... which (介词同先行词搭配)

　　when=during/ on/ in/ ... which (介词同先行词搭配)

　　1. where是关系副词，用来表示地点的定语从句。

　　2. when引导定语从句表示时间［注］值得一提的是，表示时间“time"一词的定语从句只用when引导，有时不用任何关系代词，当然也不用that引导。

　　By the time you arrive in London, we will have stayed there for two weeks. I still remember the first time I met her. Each time he goes to business trip, he brings a lot of living necessities, such as towels, soap, toothbrush etc。

　　3. 当从句的逻辑主语是some, any, no, somebody, anybody, nobody, something, anything, everything或nothing时，常用there is来引导

　　There is somebody here who wants to speak to you. 这里有人要和你说话。

一般来说，非限制性定语从句有明显的句型分割符号。

定语从句有限制性和非限制性两种.限制性定语从句是先行词不可缺少的部分.去掉它主句意思往往不明确,非限制性定语从句是先行词的附加说明.去掉了也不会影响主句的意思.它与主句之间通常用逗号分开.例如: This is the house which we bought last month. 这是我们上个月买的那幢房子.(限制性) The house. which we bought last month. is very nice.这幢房子很漂亮.是我们上个月买的.(非限制性) 2) 当先行词是专有名词或物主代词和指示代词所修饰时.其后的定语从句通常是非限制性的.例如: Charles Smith. who was my former teacher. retired last year. 查理·史密斯去年退休了.他曾经是我的老师. My house. which I bought last year. has got a lovely garden. 我去年买的的那幢房子带着个漂亮的花园. This novel. which I have read three times. is very touching. 这本小说很动人.我已经读了三遍. 3) 非限制性定语从句还能将整个主句作为先行词. 对其进行修饰. 这时从句谓语动词要用第三人称单数.例如: He seems not to have grasped what I meant. which greatly upsets me. 他似乎没抓住我的意思.这使我心烦. Liquid water changes to vapor. which is called evaporation. 液态水变为蒸汽.这就叫做蒸发. 说明:关系代词that和关系副词why不能引导非限制性定语从句. 1)介词后面的关系词不能省略. 2)that前不能有介词. 3) 某些在从句中充当时间.地点或原因状语的"介词+关系词"结构可以同关系副词when 和where 互换. This is the house in which I lived two years ago. This is the house where I lived two years ago. Do you remember the day on which you joined our club? Do you remember the day when you joined our club? 由as. which 引导的非限定性定语从句.as和which可代整个主句.相当于and this或and that.As一般放在句首.which在句中. As we know. smoking is harmful to one＇s health. The sun heats the earth. which is very important to us.