定语从句

引导定语从句的关系代词有that、which、who（宾格whom）、所有格whose和关系副词 where、when、why等

关系代词或关系副词在定语从句中充当一个成分，关系代词that、which、who、whom等在从句中分别作主语或宾语，whose在从句中作定语，而关系副词when、where、why等在从句中作状语

【举例】I will never forget the days when/in which we worked together.

【解析】在句中，表示时间的名词the days在从句中充当的是状语，所以用关系副词when来代指，引导定语从句修饰先行词the days。表示地点或原因的名词如果在从句中作状语，则用关系副词where 或why来代指；如果在从句中作动词的宾语，则用which或that来代替。 

【举例】①This is the factory where/in which I worked.（作状语）②This is the factory that/which I visited years ago.（作宾语） 

注：当先行词为time,reason, place时，引导词可以省略。

【举例】This was the first (when/what) I had serious trouble with my boss. That is the reason (why) I did it. This is the place (where) we met yesterday.  另外，定语从句中谓语动词的数应与先行词的数相一致。

【举例】①Mr. Jackson is the only foreigner that is present at the party.②He is one of the students who were praised by the teacher.