定语从句中的关系词的选择,通过两个步骤来定：
1、找出先行词,也就是被定语从句修饰的词.如：
2、判断先行词在从句中起什么句子作用,即在从句中充当什么成分.
分析如下句子：
What was the name of the man who lent you the money
借钱给你的那人叫什么名字?（定语从句修饰先行词the man,在从句中当主语）
He who laughs lst laughs best.
谁笑到最后谁笑得最好.（定语从句修饰先行词he,在从句中当主语）
There are some people whose faces you can never forget.
有些人,他们的脸你永远难以忘怀.（定语从句修饰先行词people,在从句中当定语,修饰faces）
I recently went back to the town where I was born.
我最近曾回过一次我出生的城市.(先行词是the town,在从句中表示出生的地点,当地点状语,有where,where = in which)
Please tell me the reason why you missed the plane.
请告诉我你误机的原因.(先行词是the reason,在从句中表示missed the plane 的原因,当状语,用why,why = for which)
I still remember the day when I first came to this school.
我仍然记得我第一次来到这所学校的那一天.(先行词是the day,在从句中表示came to this school的日子,当时间状语,用when,when= on which)
特别提醒：找出先行词在从句中当什么成分,特别是表示时间、地点和原因的名词!因为它们在从句中可以是表示时间、地点或原因,但它们也可以在从句中当主语,宾语或其它句子成份.
如：
This is the factory where I worked ten years ago.（工作的地点当状语）
Thisi is the factory that/ which we visited two days ago.（当visit 的宾语）
This is the factory that/ which makes TV sets. (当主语)
This is the reason why he didn't come. (当didn't come的原因,状语)
This is the reason that/which he gave us.(当gave的宾语)
