高中英语语法系列：定语从句知识要点1.关系代词和关系副词的选用2.限制性定语从句和非限制性定语从句的区别3.几组的关系词特殊用法一、定义：在复合句中，修饰名词或代词的从句叫做定语从句。
The happy man who lives next to me sells vegetables.You must do everything that I do.被定语从句修饰的词，叫先行词。
比如上面两句中的man和everything.引导定语从句的词，叫关系代词和关系副词。
比如who,whom,that,which,wh ere,when,why等关系词三重作用：①连接主从句；②指代先行词；③在定语从句中担任句子成分。
The man who lives next to me sells vegetables.该句中，who lives next to me是定语从句，修饰先行词the man，“who”是引导定语从句的关系词，代替先行词the man，在定语从句中作主语。
二、关系词引导定语从句的关系代词有who,whom,which,that,whose,as等和关系副词w here,when,why等。
关系代词和关系副词在定语从句中担任句子成分。
1.用关系代词that,which,who,whom引导的定语从句who指人，用作主语whom指人，用作宾语which指物，用作主语、宾语皆可that指人和物，用作主语、宾语皆可The teacher who visits our school today is from Guangzhou.Mrs Read is the person whom you should write to.They planted some trees which didn’t need much water.The fish(which)we bought this morning were not fresh.A plane is a machine that can fly.The noodles(that)I cooked were delicious.2.用关系代词whose引导的定语从句：先行词既可指人，也可指物，一般译为“谁的”“什么东西的”，请看例子The room whose window faces south is mine.3.用关系副词when、where、why引导的定语从句(1)when在从句中作时间状语October lst,1949is the day when(=on which)the People’s Republic of China was founded.(2)where在从句中作地点状语I recently went to the town where(=in which)I was born.(3)why在从句中作原因状语The reason why(=for which)he was late was that he missed the train.高考试题中对于where的考查趋于复杂，从先行词为明显的“地点”转为“地点的模糊化”。
事实上，对于where这个词，不能只理解为表地点。
当先行词为situa tion,case,stage,point等，且关系词在定语从句中作状语时，要用到关系副词where引导。
way(方式，方法)后常用in which或that引导定语从句，也可省略：They have reached the point where they have to separate with each other.他们已经到了必须分手的地步了。
Do you know the way(in which/that)he worked out the problem?三、限制性定语从句和非限制性定语从句的区别相同点：都属于定语从句不同点：①形式上：有无逗号。
限制性定从无逗号。
非限制性定从，有逗号。
②意义上：限制性定从对先行词起修饰限制作用；非限制性定从起补充说明作用。
He has found the book(that)he was looking for.Yesterday I met Li Ping,who seemed to be very busy.He told me a story yesterday，which I think is very interesting.(which指a s tory)Tom has made great progress,which makes me very happy.(which指逗号前面整句话意思)四、几组关系词的特殊用法1.限制性定语从句中，用关系代词that不能用which的情况：①当先行词是指物的不定代词all,little,few,much,everything,anything,nothing,none,someDo you have anything that you want to say for yourself?你有什么要为自己要说的吗？②当先行词前面有the only,the very(恰恰，正好),any,every,some,no,all,f ew,little,much,the right,the last,just等修饰时。
This is the very bus that I’m waiting for.③当先行词是形容词最高级或先行词的前面有形容词最高级修饰时。
This is the most interesting film that I’ve ever seen.这是我曾经看过的最有趣的电影。
④当先行词是序数词或它前面有序数词修饰时。
This train is the last that will go to Suzhou.这是去苏州的最后一趟火车。
⑤当先行词既有人又有物时。
Do you know the things and persons that they are talking about?你知道他们正在谈论的人和事吗？⑥当主句的主语是疑问句who或which时，Which is the bike that you lost?哪辆是你丢的自行车？Who is the boy that won the gold medal?赢得金牌的那个男孩是谁？⑦有两个定语从句时，其中一个关系代词宜用which,另外一个宜用that.They secretly built up a small factory,which produced things that could cause pollution.⑧当先行词在主句中作表语，而关系代词在从句中也作表语时。
Shanghai is no longer the city that it used to be.上海不再是过去的那座城市了。
⑨主句是there be句型且关系词在从句中作主语用，用that不用which引导。
There is a seat in the corner that is still available.2.当先行词指事或人时，定语从句中关系代词用which不用that的情况：①在非限制性定语从句中，只用which,不用thatHe broke my cup,which made me angry.他打破了我的杯子，这使我很生气。
②当动词短语中的介词提前时，只用which,不用that.This is a house in which Lu Xun once lived.这是鲁迅曾住过的房子。
注意：在一些固定搭配的动词短语中，由于动词和介词不可分割，因此不能把介词置于关系代词之前。
This is the pen(which/that)I’m looking for.这是我正在寻找的那只钢笔。
3.只用who而不用that引导定语从句的情况①先行词是指人的不定代词，如one,ones,anyone,no one,those,all,nobody, anybody,none等时，用who不用that.People all like those who have good manners.人们都喜欢那些有礼貌的人。
②在there be结构中，先行词指人时，多用whoThere are some people who want to have holidays in Hainan.有一些想去海南度假的人。
③在非限制定语从句中，指人且作主语时，用who不用thatProfessor Wang,who is over sixty,still works hard day and night.4.由as引导的定语从句①such+名词+as…像…一样的，像…之类的②the same+名词+as…和…同样的其中as可作为关系代词在从句中充当主语、宾语或表语。
We have found such materials as are used in their factory.我们已经找到了像他们工厂里用的那种材料。
(as作主语)These houses are sold at such a low price as people expected.这些房子以人们预料的那样的低价出售。
(as作宾语)He is not the same man as he was.他和过去不同了。
(as作表语)注意such…as…引导的定语从句与such…that…引导的状语从句的区别：①He is such a clever boy as everyone likes.(定语从句)他是一个人人都喜爱的聪明孩子。
②He is such a clever boy that everyone likes him.(状语从句)他是一个如此聪明的孩子，以至于人人都喜爱他。
第一个句子中as引导的是定语从句，因为从句中缺成分；而第二个句子中that 引导的是状语从句，从句中不缺任何成分。
5.“介词+关系代词”引导的定语从句(若介词放在关系代词前，关系代词指人时只可用whom,不可用who,that；关系代词指物时只可用which，不可用that。
关系代词是所有格时用whose。
方法：①根据定语从句中动词的固定搭配来确认“介词+关系代词”中的介词；②根据先行词来确认“介词+关系代词”中的关系代词The school(which/that)he once studied in is very famous.The school in which he once studied is very famous.他曾经就读过的学校很出名。