一、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。 如: 

①I will never forget the days when/in which we worked together. 

②I will never forget the days which/that we spent together.

解析:在句①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;

而在句②中,表示时间的名词the days在从句中充当的是动词spent的宾语,所以用关系代词that或which来代指。  

同样,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。 如: 

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。如: 

①This was the first (when/what) I had serious trouble with my boss. 

②That is the reason (why) I did it. 

③This 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。如: 

①Mr. Jackson is the only foreigner that is present at the party.

②He is one of the students who were praised by the teacher. 

解析:在句①中,先行词foreigner被only修饰,强调只有一个,所以从句中谓语动词用单数形式,而在句②中,who引导的定语从句修饰先行词the students,为复数,所以从句谓语动词应为复数。