A good studentA developing countryA developed countryA 5-star friendA man named ChuckA language widely used定语从句：修饰某一名词或代词的主谓结构(完整的基本句子结构-----五种句型)。
↓↓（主句之中）先行词关系词+其它成分↓在定语从句中必须担当一个成分。
↓定语从句中缺啥就补啥定语从句(The Attributive Clause)((二)关系代词的作用1. 关系代词：用来连接定语从句，并在从句中代表先行词的代词。
先行词是物：which that 先行词是人：who that※由who, whom, whose引导的定语从句。
这类定语从句中who用作主语，whom作宾语，whose作定语。
e.g. This is the man who helped me. The doctor (whom) you are looking for is in the room.Do you know the man whose name is Wang Yu?※在定语从句中，若先行词指人，其关系代词可用who, whom, 也可用that。
e.g. The girl who/that is speaking at the meeting is our monitor.The boy (who/whom/that) you saw just now is my brother.3. 关系代词的具体用法及作用1).who指人，在从句中做主语。
如：The boys who are playing football are from Class One. Yesterday I helped an old man who lost his way.2). whom指人，在定语从句中充当宾语，常可省略。
如：Mr. Liu is the person (whom) you talked about on the bus. Mr. Ling is just the boy whom I want to see.注意：关系代词whom在口语和非正式语体中常用who代替，可省略。
如：The man who/whom you met just now is my friend.3). which指物，在定语从句中做主语或宾语，做宾语时可省略如：Football is a game which is liked by most boys. This is the pen (which) he bought yesterday.4). that指人时，相当于who 或whom；指物时，相当于which。
在宾语从句中做主语或宾语，做宾语时可省。
如：The number of the people that/who come to visit the city each year rises one million.Where is the man that/whom I saw this morning?5). whose通常指人，也可指物，在定语从句中做定语如：He has a friend whose father is a doctor. I once lived in a house whose roof has fallen in.The girl is my daughter. / Her work got the first prize. →The girl whose work got the first prize is my daughter.Do you know anyone? / His family is in Xi‟an. →The book is not mine. / The cover of it is red.I live in the room. / The windows of it face south. → The chair has been repaired. / The leg of it was broken.Whose引导的定语从句应注意以下几点：①whose引导定语从句，其后应紧跟名词，构成名词短语。
如：That‟s the child whose father is an engineer.② whose引导定语从句，其先行词不仅可以指人，还可以指物。
如：Mr King, whose legs were badly hurt, was quickly hurt, was quickly taken to hospital.I saw a tree whose leaves were black with disease.③ whose在定语从句中与它所修饰的名词一起可作介词的宾语，可以与介词放在先行词与从句之间。
如：The boss in whose department Mr King worked had heard about the accident.Tom, on whose bike I went to school is a friend of mine.④whose的先行词指物时, 可用of which代替, 但词序不同，即whose+名词=the +名词+of which如：He lives in the room whose window( the window of which) faces south.The classroom whose door is broken will soon be repaired.the door of whichThe classroom the door of which is broken will soon be repaired.Do you like the book whose cover is yellow? Do you like the book the color of which is yellow?(三)在下列情况下只用that，不用which①先行词是all, everything, nothing, anything, little, much, the one等不定代词时，something两者均可。
如：There is nothing (that) I can do. I mean the one that was brought yesterday.Is there anything that I can do for you?②先行词被all, any, every, no, some, little, much，few，one of 等词修饰时，如：I have read all the books (that) you gave me. You may take home any of these books that you like.③先行词被序数词first, last, next等或形容词最高级修饰时，如：The first thing that we should do is to help him. This is the best novel (that) I have ever read.She is the most careful girl that I‟ve ever known.④先行词被the only, the very(正是,恰是), the same, the last修饰时，如：The white flower is the only one (that) I really like. This is the very book (that) I want to find.The last place (that) we visited was the hospital. This is the same watch that I lost yesterday.That‟s the very tool that we are looking for.⑤当先行词有两个或两个以上时,既有人又有物,定语从句用that 引导(that既可指人也可指物)如：He talked about the teachers and schools that he had visited.They talked about the things and friends that they could remember.⑥当主句是以who，which或what开头的特殊疑问句时。
如：Who is the man that is reading the newspaper over there? Which of us that knows anything does not know this?Who is the man that is standing over there? Which is the tool that you are looking for?What did you hear that made you so angry?⑦当先行词是系动词b e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 a go. He is no longer the man that he used to be.It‟s a book that will help you a great deal.The village is no longer the one that it used to be.⑧当主句以There be…结构开头时，或关系代词在there be…结构中作实际主语，且先行词为物如：There is a seat in the corner that is still free. There are two tickets of the film that are for you.⑨当先行词是基数词时如：Y esterday I caught two fish and put them in a basin of water. Now you can see the two that are still alive. (四). 在下列情况下只用who(m)，而不用that：①关系代词在从句中作主语时，多用who.如：Do you know the man who spoke just now? The doctor who treated me was very experienced.②当先行词是one, ones, any, few, all,anyone, anybody, someone, somebody, everyone, everybody等词时。