定语从句(Attributive Clauses)在句中做定语，修饰一个名词或代词，被修饰的名词,词组或代词即先行词。定语从句通常出现在先行词之后，由关系词(关系代词或关系副词)引出。
关系代词有:who, whom, whose, that, which等。
关系副词有:when, where, why等。
18.1 关系代词引导的定语从句 关系代词所代替的先行词是人或物的名词或代词，并在句中充当主语、宾语、定语等成分。关系代词在定语从句中作主语时，从句谓语动词的人称和数要和先行词保持一致。
1)who, whom, that 这些词代替的先行词是人的名词或代词，在从句中所起作用如下: Is he the man
who/that wants to see you? 他就是你想见的人吗?(who/that在从句中作主语) He is the man whom/ that I saw yesterday. 他就是我昨天见的那个人。(whom/that在从句中作宾语)
2) Whose 用来指人或物，(只用作定语, 若指物，它还可以同of which互换), 例如: They rushed over to help the man whose car had broken down. 那人车坏了，大家都跑过去帮忙。 Please pass me the book whose (of which) cover is green. 请递给我那本绿皮的书。
3)which, that 它们所代替的先行词是事物的名词或代词，在从句中可作主语、宾语等，例如: A prosperity which / that had never been seen before appears in the countryside. 农村出现了前所未有的繁荣。(which / that在句中作宾语) The package (which / that) you are carrying is about to come unwrapped. 你拿的包快散了。(which / that在句中作宾语
18.2 关系副词引导的定语从句 关系副词可代替的先行词是时间、地点或理由的名词，在从句中作状语。
1)when, where, why 关系副词when, where, why的含义相当于"介词+ which"结构，因此常常和"介词+ which"结构交替使用，例如: There are occasions when (on which) one must yield. 任何人都有不得不屈服的时候。 Beijing is the place where (in which) I was born. 北京是我的出生地。 Is this the reason why (for which) he refused our offer? 这就是他拒绝我们帮助他的理由吗?
2)that代替关系副词 that可以用于表示时间、地点、方式、理由的名词后取代when, where, why和"介词+ which"引导的定语从句，在口语中that常被省略，例如: His father died the year (that / when / in which) he was born. 他父亲在他出生那年逝世了。 He is unlikely to find the place (that / where / in which) he lived forty years ago. 他不大可能找到他四十年前居住过的地方。 用关系代词，还是关系副词完全取决于从句中的谓语动词。及物动词后面无宾语，就必须要求用关系代词;而不及物动词则要求用关系副词。例如: This is the mountain village where I stayed last year. I'll never forget the days when I worked together with you. 判断改错(注:先显示题，再显示答案，横线;用不同的颜色表示出。) (错) This is the mountain village where I visited last year. (错) I will never forget the days when I spent in the countryside. (对) This is the
mountain village (which) I visited last year. (对) I'll never forget the days (which) I spent in the countryside. 习惯上总把表地点或时间的名词与关系副词 where, when联系在一起。此两题错在关系词的误用上。
定语从句(Attributive Clauses)在句中做定语，修饰一个名词或代词，被修饰的名词,词组或代词即先行词。定语从句通常出现在先行词之后，由关系词(关系代词或关系副词)引出。
关系代词有:who, whom, whose, that, which等。
关系副词有:when, where, why等。
18.1 关系代词引导的定语从句 关系代词所代替的先行词是人或物的名词或代词，并在句中充当主语、宾语、定语等成分。关系代词在定语从句中作主语时，从句谓语动词的人称和数要和先行词保持一致。
1)who, whom, that 这些词代替的先行词是人的名词或代词，在从句中所起作用如下: Is he the man
who/that wants to see you? 他就是你想见的人吗?(who/that在从句中作主语) He is the man whom/ that I saw yesterday. 他就是我昨天见的那个人。(whom/that在从句中作宾语)
2) Whose 用来指人或物，(只用作定语, 若指物，它还可以同of which互换), 例如: They rushed over to help the man whose car had broken down. 那人车坏了，大家都跑过去帮忙。 Please pass me the book whose (of which) cover is green. 请递给我那本绿皮的书。
3)which, that 它们所代替的先行词是事物的名词或代词，在从句中可作主语、宾语等，例如: A prosperity which / that had never been seen before appears in the countryside. 农村出现了前所未有的繁荣。(which / that在句中作宾语) The package (which / that) you are carrying is about to come unwrapped. 你拿的包快散了。(which / that在句中作宾语
18.2 关系副词引导的定语从句 关系副词可代替的先行词是时间、地点或理由的名词，在从句中作状语。
1)when, where, why 关系副词when, where, why的含义相当于"介词+ which"结构，因此常常和"介词+ which"结构交替使用，例如: There are occasions when (on which) one must yield. 任何人都有不得不屈服的时候。 Beijing is the place where (in which) I was born. 北京是我的出生地。 Is this the reason why (for which) he refused our offer? 这就是他拒绝我们帮助他的理由吗?
2)that代替关系副词 that可以用于表示时间、地点、方式、理由的名词后取代when, where, why和"介词+ which"引导的定语从句，在口语中that常被省略，例如: His father died the year (that / when / in which) he was born. 他父亲在他出生那年逝世了。 He is unlikely to find the place (that / where / in which) he lived forty years ago. 他不大可能找到他四十年前居住过的地方。 用关系代词，还是关系副词完全取决于从句中的谓语动词。及物动词后面无宾语，就必须要求用关系代词;而不及物动词则要求用关系副词。例如: This is the mountain village where I stayed last year. I'll never forget the days when I worked together with you. 判断改错(注:先显示题，再显示答案，横线;用不同的颜色表示出。) (错) This is the mountain village where I visited last year. (错) I will never forget the days when I spent in the countryside. (对) This is the
mountain village (which) I visited last year. (对) I'll never forget the days (which) I spent in the countryside. 习惯上总把表地点或时间的名词与关系副词 where, when联系在一起。此两题错在关系词的误用上。