定语从句一、 定义概念：定语是用来修饰限定名词或者代词的成分，用来说明所修饰词的品质特征。可以充当定语的有形容词、名词、代词、数词、副词、不定式、动名词、分词、介词短语，当由一个句子充当定语时，我们把这个句子叫做定语从句，定语从句属于形容词性从句。1. she is a beautiful girl.（形容词）2. This is an apple tree.（名词）3. Who is that girl?（代词）4. I have three books.（数词）5. The girl over there is his sister.（副词）6. I have a lot of homework to do.（不定式）7. There is a swimming pool.（动名词）8. The baby sleeping in the room is 10 years old.（现在分词）9. The house built last week needs repairing.（过去分词）10. The girl in red is my sister.（介词短语）以上10个句子中分别列举了可以做定语的词类。下面列举定语是句子的情况，也就是定语从句。定语从句需要掌握四个方面：主句、先行词、关系词、从句。定语从句的先行词一定是名词性的内容（名词、代词；代词其实是名词性的一种）1. I know the girl who is beautiful.主句：I know the girl.先行词：the girl关系词：who（在从句中做主语）从句：who is beautiful.2. I lost the book that/which cost me 10 yuan.主句：I lost the book.先行词：the book关系词：that/which（在从句中做主语）从句：That/which cost me 10 yuan.3. She found a dog whose eyes are blue.主句：She found a dog先行词：a dog关系词：whose（在从句中作定语）从句：whose eyes are blue4. I still remember the day when I graduate from school.主句：I still remember the day先行词：the day关系词：when（在从句中做时间状语）从句：when I graduate from school.5. Do you know the place where he is from.主句：Do you know the place先行词：the place关系词：where（在从句中做地点状语）从句：where he is from.6. Thats the reason why he is late for school.主句：Thats the reason先行词：the reason关系词：why（在从句中做原因状语）从句：why he is late for school由以上例子可以看出，定语从句中有不同的关系词。关系词分为两大类：关系代词和关系副词。关系代词：that、which、who、whom、whose关系副词：when、where、why关系词的用法关系代词：that 既可指人，也可指物，作主语，不能省略；作宾语，可以省略。which指物，作主语，不能省略；作宾语，可以省略.who 指人，作主语，不能省略；作宾语，可以省略whom指人，做宾语，前面没有介词时可以省略，如果有介词则不能省略whose只能作定语，不能省略关系副词：when做时间状语where做地点状语why做原因状语关系词详细讲解把两个句子合并成定语从句，两个句子一定要有一个共同的名词部分，才能建立关系，首先找到两个句子共同的名词部分，把第二个句子共同部分用关系词来代替，由此可以把两个句子连接在一起，形成定语从句。一、 关系代词that和whichthat:既可指人，也可指物，作主语，不能省略；作宾语，可以省略。which指物，作主语，不能省略；作宾语，可以省略.1.This is a dream.The dream will never come true.第一个句子中的 a dream和第二个句子中的the dream是重复部分，dream指物，由于在从句中做主语，可以用关系代词that/which来代替the dream，就可以改写为：This is a dream that/which will never come true.主句：This is a dream.先行词：a dream关系词：that/which（在从句中做主语，不可省略）从句：that/which will never come true.2. He likes the present. His mother bought it for him. 第一个句子中the present和第二个句子中it是重复部分，present指物，由于在从句中做宾语，可以用关系代词that/which来代替it，就可以改写为：He likes the present that/which his mother bought for him.主句：He likes the present.先行词：the present关系词：that/which（在从句中做宾语，可以省略）从句：that/which his mother bought for him.二、 关系代词who,whom和whosewho 指人，作主语，不能省略；作宾语，可以省略whom指人，做宾语，前面没有介词时可以省略，如果有介词则不能省略whose只能作定语，不能省略1.That is the boy. He did a very good job.第一个句子中the boy 和第二个句子中he是重复部分，boy指人，由于在从句中做主语，可以用关系代词that/who来代替he,就可以改写为：That is the boy that/who did a very good job.主句：That is the boy先行词：the boy关系词：that/who（在从句中做主语，不可省略）从句：that/who did a very good job.2.Do you know the old man. They talked about the old man.在第一个句子中the old man 和第二个句子中 the old man 是重复部分，old man指人，由于在从句中做宾语，可以用关系词that/who/whom来代替the old man就可以改写为：Do you know the old man that/who/whom they talked about?主句：Do you know the old man 先行词：the old man关系词：that/who/whom从句：that/who/whom they talked about3. We all like the boy.The boys name is Tom.在第一个句子中the boy和第二句中the boys是重复部分，由于the boys是所有格的形式，所以用关系代词whose来代替the boys,就可以改写为We all like the boy whose name is Tom.主句：We all like the boy先行词：the boy关系词：whose（作定语来修饰the boy）从句：whose name is Tom.注意1：关系代词做主语时，从句的谓语动词在人称和数上保持一致1.Anyone who finishes homework can go home.关系词who在从句中做主语，谓语动词取决于先行词anyone，anyone属于不定代词，谓语动词用单数，所以finishes用单三形式。2. I found the dogs that were sleeping in the garden.关系词that在从句中做主语，谓语动词取决于先行词the dogs，the dogs是负数形式，由于时态是过去时，所以be动词用were.注意:2：关系代词whom做宾语不能省略的情况当关系代词whom前有介词时，whom不能省略。如果介词放在句子末尾，则whom可以省略。1.I know the boy about whom they are talking.（whom前有介词about，所以whom不可以省略）=I know the boy whom they are talking about.（whom前无介词，可以省略）2. She is the girl with whom I usually go shopping .（whom前有介词with，所以whom不可以省略）=She is the girl whom I usually go shopping with.（whom前无介词，可以省略）注意3：关系词只能用that的情况1.当先行词是 all,much，any, few, little, none, anything, everything, nothing something或被它们修饰时 （1）Thats all that I know. （2）Is there anything that I can do for you? （3）He answered few questions that the teacher asked.2.当先行词被形容词最高级或序数词修饰时（1）That is the most interesting book that I have ever read.（2）The first thing that I should do is to review my lessons.3. 当先行词有the very, the only, the same，the last等修饰时。（1）Thats the only thing that I can do now.（2）These are the very words that he used.4. 当主句以 who 或 which开头时，为了避免重复，定语从句的关系词用 that, 而不用 which 或 who.（1）Who is the girl that spoke to you just now?（2）Which is the pen that you lost ?5.先行词同时包括人和物时，关系词用that.（1）The man and his dog that I always meet are standing by the gate.（2）Can you tell me the