曾在气院呆过
先行词是被定语从句所修饰的名词、代词。在定语从句中充当一定的部分。之所以称它为先行词，是因为修饰它的定语从句总是放在它之后，先行词总是出现在定语从句之前，而不同于普通形容词修饰名词时，形容词位于名词之前。
例句:This is the book which I am looking for.
它是我正在寻找的书。
其中的"the book"是先行词，"which"是引导词。
例句:He is Mr. Robertson who comes from England.
他是来自英国的罗伯森先生。
其中的"Mr. Robertson"是先行词，"who"是引导词。
被定语从句修饰的名词、代词称为先行词。我们可以这样认为，之所以称它为先行词，是因为修饰它的定语从句总是放在它之后，先行词总是出现在定语从句之前，而不同于普通形容词修饰名词时，形容词位于名词之前。
Don’t forget the bookthat I told you to bring.（“the book”为先行词）
别忘了把我让你带的书带过来。
关系词
引导定语从句的词被称为关系词。关系词根据其在定语从句中的功能可分为关系代词和关系副词。关系代词在定语从句中作主语、宾语、表语、定语等，关系副词在定语从句中作状语。
含有定语从句的句子一般分为两层：即主句层（第一层），定语从句层（第二层）。
璐璐308738
先行词:是在定语从句中,被定语从句所修饰的名词.例如: He is a teacher who teach our English.在这里定词从句who teach our English是来修饰前面的名词teacher.所以teacher就是一个先行词. 再说下它的用法： 1、先行词指人时，引导词可用Who,Whom,及that,其中当引导词在句中作主语时用Who或that；当其充当宾语时用whom或that，在非正式宾语中也可用who，也可省略。 a That boy who/that broke the window is called Tom. b The person to whom you just talked is Mr Li. b 句可改为：The person(that/whom/who)you just talked to is Mr Li. 2、先行词指物时，引导词用that或which a.They planted the trees which didn’t need much water. b .The fish (which)we bought were not fresh. 3、先行词指时间时，引导词用When/on which或in which a.I still remember the day when/on which I first came to Bei jing. b.I'll never forget the year when/ on which we worked on the farm. 4、先行词指地点时，引导词用Where或in which This is the house where/in which we lived last year. 或:This is the house that/which we lived in last year. 5、whose在定语从句中作定语时，可用来指人，也可以用来指物，如: a.This is the boy whose mother died a month ago. b.This is the house whose windows were broken.此句可改成： This is the house the windoues of which were broken. 6、先行词表示原因时，引导词用why,如: The reason why he was late for school was that he had been knocked down by a bike.
