定语从句关系词通常在什么情况下选择that、who、which等和where、when、why等要详细的区别还有什么关系

为什么会有限制性和非限制性定语从句的出现?中英文定语从句词序有什么区别.
定语从句有两个功能,一个是限制以帮助人们寻找区分出某人或某物..另一功能是修饰形容.,就象中文里的“伟大的,光荣的,正确的”的抒情描述一样.我们要在一群女孩里找出一个叫罗勤燕的女孩,那就必须对这群女孩子进行限制,找出罗勤燕的一些个性特征：如：The girl who is very tall and beautiful is Luo Qinyan.那个又高又漂亮的女孩就是罗勤燕.“又高又漂亮的女孩”就是限制性定语从句,它能帮助人找出罗勤燕.如果“罗勤燕”当先行词,就不能用限制性,必须用非限制性.非限制只能是补充说明,Luo Qinyin,who is very tall ,is our monitor .这句话翻译与限制性完全不同:罗勤燕是我们的班长,她很高.”她很高.”是补充说明,要翻译成另一句话,它没有帮助寻找区分的功能.,而限制性定语从句只是一句话..教室里的女孩那么多个,不限制就找不出罗勤燕,罗勤燕只有一个,不能再限制了.
2.限制性定语从句的特点:在中文中后置的被修饰限制的名词在英语中都是前置的,放在从句前当先行词.而定语从句又总是紧紧放在先行词后面.这就出现了与中文不一样的词序：主句和从句混在一起,主句的谓语动词与从句的谓语动词可紧紧地凑近混合在一起.
1）The girl who is dancing dances well.
2）The thing that I tasted tastes sweat
3）The girl at whom I looked looks beautiful.
从句的动词与主句的动词紧挨在一起,很容易令学生感到混乱,别扭,很容易出现分不清主句,从句,不懂句子是什么意思的问题.请试翻译以下句子:
1}.“The teacher pointed out that that that that student wrote was in wrong place .”
2).The person who is brave is afraid to look at my eyes.
3)I can can the can that is smaller into the can that is bigger .
3).The house whose windows are big is big .
4)The students who didn’t come didn’t get the money .
5)The boy who is tall is shorter than some classmates in the university in the north.
3．先行词,引导词,从句的主语这三个位置都是考试中惯考的三类难点.有两个技巧我们必须要掌握：1.凡是含有定语从句的复合句,都必须有两个主语,两个谓语动词,如果少一个主语或少一个谓语动词,都是不]正确的句子.象我们这次甲级联赛中都出现这样的句子错误：The student who is very tall and beautiful .
1）that ,which ,who ,whose,where,when都是考试惯考的引导词.
在不定代词当先行词或修饰先行词,最高级,序数词修饰先行词时,只能用that,不能用which.非限制性定语从句,紧跟在介词后面的关系代词只能用which,不能用.that.
a.引导词在当从句宾语时可以省略.但先行词,从句主语却不能省略,这个要注意.
1}______(a.the one b.that c.which d.who) you talked to is talking to us now.
2}I like the book_________(a.you b.that c.the one d.who)talked about .
b.which可以指代前面的整句话,这时which前面总是有个逗号,which在从句中大多当主语,偶尔也有在从句中当宾语的.
1)She tore my photo_____{a,which b.who c.which d.whose} I took in Guangzhou .
2) She tore my photo_____{a,which b.who c.which d.whose} made me angry .
3}I sat on the chair _____{a,which b.who c.which d.whose}legs are broken .
4.在表示地点的名词当先行词时,其后的定语从句中的动词大多数是不及物的,都是用where或介词+which引导从句.只有visit ,build ,buy ,sell ….等及物动词可以用在地点名词后的定语从句中,那时只能用关系代词which,that,当宾语可以省略.
1)The school _____I studied ten years ago becomes more and more beautiful.
2) The school _______I visited ten years ago becomes more and more beautiful.
3)This is the house in _____ Mao live many years ago.
4) This is the house_______ Mao built many years ago .
5)The bookshop ______he works is very large .
6)The bookshop ______ he bought last year is very large .
7)The bookshop ______he bought the book is very large .
5.在表示时间的名词当先行词时,其后的定语从句中的动词也大多数是不及物的,都是用when或介词+which引导从句,只有spend,remember,forget,等少数几个及物动词词可以用在时间名词引导的定语从句中,它可以带时间名词当宾语,这时从句只能用which ,that引导,当从句宾语时that ,which当宾语可以省略以省略.
1）I’ll never forget the days _______ I lived in Beijing .
2) I’ll never forget the days _______ I spent in Beijing .
3)The time _____ you forget is the day after tomorrow .
4)The time _____you’ll meet me in Beijing is the day after tomorrow .
5)The time _____ you remembered to stop heating the soup is too late .
6)The time _____you remembered is 9:30 .

我建议您去百度文库里面去搜下
这样区别解释多得是啊
并且很全面呢

定语从句中的关系词的选择，通过两个步骤来定： 1、找出先行词，也就是被定语从句修饰的词。如： 2、判断先行词在从句中起什么句子作用，即在从句中充当