1、将一句话分成两个句子，主干句和跟从句
eg:我特别讨厌我遇见他的那个城市。
<1> I really hate the city. 我特别讨厌那个城市。
<2> I met him in the city.我在那个城市遇见他。
2、将两句合成一句话
I really hate the city I met him in the city.
3、找出同类项，将后者同类the city找出，待用关系词代替
I really hate the city I met him in the city.
4、合并同类项，选择关系词
相同的名词/代词为先行词，将后者同类词用关系词取代，属性为人或者拟人用Who属性为物用which。
I hate the city I met him in which.
关系词一般跟在先导词后面，整理为
I hate the city in which I met him.
5、where本身作为地点副词可以描述地点，为了精简，则in which可以替换为where。
简化为：
I hate the city where I met him
6、则关于地点的定语从句，如有“介词+which”可以用“where”代替，地点不等于where，必须“介词+which”
1、我都忘记你过来的日子了。
<1>分
我忘记日子了。
你在那个日子来的。
<2>合
I have forgot the day you came on the day.
I have forgot the day on which you came.
I have forgot the day when you came
则关于时间的定语从句，如有“介词+which”可以用“when”代替，时间不等于when，必须“介词+which”。
1、我有一条眼睛是蓝色的小狗。
<1>分
I have a dog.
A dog’s eyes are blue.
<2>合
I have a dog a dog’s eyes are blue
I have a dog who’s eyes are blue
who的所有格为whose
则句子变成
I have a dog whose eyes are blue
1、我不理解他离开我的原因。
<1>分
我不理解原因。
他因为这原因离开我。
<2>合
I don’t understand the reason he left me for the reason.
I don’t understand the reason he left me for which.
因Why可以描述原因，则句子变为
I don’t understand the reason he left me why.
1、我认识那个你喜欢的男孩。
<1>分：
I know the boy.
You like the boy.
<2>合
I know the boy you like the boy.
I know the boy who you like.
the boy处于句子宾语位置，则用who的宾格形式whom
则句子变为
I know the boy whom you like.
