★ There are very few but admire his talents.(关系代词but在从句中用作主语，其先行词是few, but= who don't)
用作关联词的关系副词有where, when, why等，when在定语从句中用作时间状语，其先行词是表时间的名词。如：
★ Just at the time when it became obvious that health-care resources could not possibly meet the demands being made upon them, people were demanding that their fundamental right to health-care be satisfied by the state.(关系副词when的先行词是the time)
since, before, after, as也可以用作表时间的关系副词。如：
★ At exactly the same time as this new realization of the finite character of health-care resources was sinking in, an awareness of a contrary kind was developing in western societies.(as用作关系副词)
★ Every day since she came has been most enjoyable.(since用作关系副词)
★ On the day before the war broke out he was born.(before用作关系副词)
★ The year after she left school she spent abroad.(after用作关系副词)
where在定语从句中用作地点状语，其先行词是表地点的名词。如：
★ I know the place where we can have a talk.
★ The zoo is an ideal research centre where scientists can experiment on animals to find out the causes of some disease and develop effective cures.
where的先行词可以是有地点含义的抽象名词。如：
★ He has reached a point where a change is needed.(where的先行词point是抽象名词)
why在定语从句中用作原因状语，其先行词只有reason。如：
★ That is the reason why he set up his own business.(why的先行词是reason)
★ The company refused to disclose the reason why he left.(why的先行词是reason)
有时候why可以省去。如：
★ The reason he came here is obvious.(reason后面省去why)
有时候why可以用that替代。如：
★ The reason that he failed was lack of patience.(why由that替代)
关系副词 = 介词 + which(关系代词)
where = in/at which; when = in/at which; why = for which
定语从句分为限制性定语从句和非限制性定语从句。考生注意，限制性定语从句与先行词关系密切，对它有限制性作用，因此不可缺少，如果省去，会使主句的意思不完整、不明确。限制性定语从句前面一般不用逗号。如：
★ The man who was driving the car was drunk.
★ The speech which was made by the Minister made his supporters delighted.
★ The police told us that he was the only person that was suspected.
★ This is the place where the three roads meet.
★ I shall never forget the day when she was born.
★ The reason why he was late was unknown.
★ The house whose windows are broken is Mr. A's.
非限制性定语从句也称为描述性定语从句。非限制性定语从句只与先行词有一种松散的修饰关系，在口语中用停顿的方法表示，在书面语中用逗号分开。因此从句中的关系代词不能省略。that一般不引导非限制性定语从句。如：
★ Water, which is a clear liquid, is the giver and taker of life.
★ They gave up the plan, which was a very good one.