①This is not the book of which the teacher spoke in class. (speak of 意为“谈论”，相当于talk about)
②The two things of which they felt proud were Jim’s gold watch and Della’s hair. (be / feel proud of 为固定短语，意为“以……自豪”。)
①I’ll never forget the day on which I first met him. (表示具体的某一天，介词用on)
②The boy pointed to the direction in which he would run. （“朝……方向”，介词用in）
The clever boy made a hole in the wall, through which he could see what was happening inside the house.
（1）The school（that/which）he once studied in is very famous。
“that/which”可以省略。= The school in which he once studied is very famous。“which”不可省略。
（2） 含有介词的短语动词一般不拆开,介词仍放在短语动词的后面。如：look for, look after, take care of等。T This is the watch which/that I am looking for。（T=正确）F This is the watch for which I am looking。（F=错误）
（1）The man with whom you talked is my friend.（T）The man famous.
（2）I bought many books yesterday, three of which are written by Lu Xun.
例：A doctor who looks after people's health。主语 谓语 先行词 定语从句修饰先行词
判断介词和关系代词方法一 : 用关系代词还是关系副词完全取决于从句中的谓语动词:不及物动词后面无宾语，就必须要求用关系副词或者是介词加关系代词；而及物动词后接宾语，则要求用关系代词。
例如： This is the mountain village where I stayed last year.
判断改错:（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。
例. Is this the museum ____ the exhibition was held?A. where B. that C. on which D. the one,解析： 主、谓、宾俱全，从句部分为句子的状语表地点，既可用副词where，又因 in the museum词组，可用介词in + which 引导地点状语。而此题中，介词on 用的不对，所以选A。
关系词的选择依据在从句中所做的成分,先行词在从句中做主、宾语时,选择关系代词（who, whom, that, which, whose）； 先行词在从句中做状语时,应选择关系副词（“where”地点状语,“when”时间状语,“why”原因状语）。