语法精讲定语从句定语从句的关系代词和关系副词的选择关键是要注意分析它们在从句中所作的句子成分，如果作主语、宾语、表语、定语，则用关系代词which,that,who,whom,whose；若作状语，则用关系副词when,where,why。
注意下列情况：1.只用that（1）当先行词是不定代词，如all,everything,anything,n othing,much,few,little,none,the one等时。
（2）先行词（指物的）前面有only,few,one of,little,no,all,every,very等词修饰时。
（3）先行词被序数词first,last,next等或形容词的最高级修饰时。
（4）当先行词既有人又有物时。
（5）当先行词是系动词be后面的表语或关系词本身是从句的表语时。
如：China isn’t the country that she used to be 50 years ago.He is no longer the man that he used to be.It’s a book that will help you a great d eal.（6）当主句是以who,which或what开头的特殊疑问句时。
（7）当主句以There be…结构开头时。
如：There is a seat in the corner that is still free.There are two tickets of the film that are for you.（8）当先行词是what时，如：What did you hear that made you so angry?（9）当先行词是基数词时。
如：Yesterday I caught two fish and put them in a basin of water.Now you can see the two that are still alive.2.只用which（1）在非限制性定语从句中充当主语或定语时。
（2）当关系代词前有介词时。
（3）当先行词本身that是时。
如：What’s that which flashed in the sky just now?3.只用who 不用that（1）先行词是one,ones或anyone时。
（2）先行词为those或被those修饰，指人时。
如：Those who learn not only from books but also through practice will succeed.（3）在there be… 的句子中，先行词为人时。
如：There is a comrade outside who w ants to see you.（4）当定语从句中又有定语从句，且先行项都为人时。
如：The student that won the first prize is the monitor who works hard.（5）当指人的先行项被一些指物的名词修饰时。
如：There’s only one student in the school who I want to see.Do you know the woman in blue with a baby on her back who is working in the fields?(6)在非限制性定语从句中指人。
如：I met a friend of mine in the street,who had just come from America.（7）定语从句中有插入语时，并不影响关系代词和副词的选择。
如：Jackson is a man who I believe is honest.He won another award,which I think is the result of his hard work.4.在定语从句中，whose作定语，其先行词既可以是人，又可以是物。
如：Lei Feng was a great communist fighter whose death was weightier than Mount Tai.Where’s the window whose glass is broken?5.as,which的比较（1）在非限制性定语从句中，均可替代整个主句或句中某个部分，在从句中作主语、宾语、表语。
如从句在主句之后，两者皆可用。
如：Grammar is not a set of dead rules,which/as I have said before.（2）如从句在主句之前，用as。
（3）如关系代词代表主句全句意思，有“正如……，就像……”之意时，用as。
如：We won the match,as we had expected.（4）当先行词被the same,such,so修饰时，用as。
如：This is the same books as you bought yesterday.（同类书）比较：This is the same book that you bought yesterday.(同一本书)考题再现【考例1】(2006江西高考，33)—Do you have anything to say for yourselves?—Yes,there’s one point ______we must insist on.A.whyB.whereC.howD./解析：此题考查定语从句引导词的选用。
the point 作介词on的宾语，因此应选用关系代词或者省略。
答案：D【考例2】(2006湖南联考) It was in the very house______was built with stones _____he spent his childhood.A.that;thatB.that;whereC.which;whereD.where;that解析：第一个空应引导定语从句，引导词在从句中作主语，且先行词由the very 修饰，故应选择that；第二空引导强调句。
答案：A【考例3】—Have you read the books?—Yes,I have read all the books______you gave me,because they are the best ones _____I have ever read.A.which;thatB.that;thatC.what;whichD.who;what解析：选项在定语从句中都作宾语，且第一个受all的修饰，第二个受形容词最高级修饰，故都使用that。
答案：B【考例4】(2006浙江高考，13)I was given three books on cooking,the first _____I really enjoyed.A.of thatB.of whichC.thatD.which解析：因the first 与three books之间是部分与整体的关系，因此应用介词of，且介词后只能用which，不用that。
答案：B【考例5】(2006全国高考Ⅰ，24) I have many friends, _____some are businessmen.A.of themB.from whichC.who ofD.of whom解析：of whom引导定语从句，of是介词提前，表示“其中的”。
先行词friends是表示人的名词，要用whom。
答案：D]【考例6】(2006天津高考，13) Last month,part of Southeast Asia was struck by floods,from_____ effects the people are still suffering.A.thatB.whoseC.thoseD.what解析：whose引导定语从句，表示effects与part of Southeast Asia是所属关系。
答案：B【考例7】(2006福建高考，22) Look out!Don’t get too close to the house _____roo f is under repair.A.whoseB.whichC.of whichD.that解析：关系代词whose表示“……的”，是关系代词who，which的所有格，因此既可指人，也可指物。
在从句中，whose作定语修饰名词，被修饰词可以是从句的主语、宾语或介词宾语。
根据句意可判断出roof与the house之间是所属关系。
答案：A【考例8】(2006天津高考，12) The Beatles, ______many of you are old enough to remember,came from Liverpool.A.whatB.thatC.howD.as解析：根据句子结构和意义可知空格处应选用一个非限制性定语从句的引导词；what 不引导定语从句，that不能用于引导非限制性定语从句；该定语从句中的引导词应作remember的宾语，排除how。
答案：D。