关于英语定语从句中充当状语成分

首先纠正你个错误,不是先行词在句子中做状语成分,才用关系副词.先行词在句子中做任何成分都可以用关系副词来引导定语从句.正确的说法是,当关系副词来引导定语从句时,关系副词在定语从句（记住是在从句当中）当中充当状语成分.具体关系副词的选用：地点名词(时间名词)＋关系副词＋定语从句,引导定语从句的关系副词主要有where,when 和why.why只能引导由名词reason作先行词的定语从句.
关系副词where和when 所引导的定语从句用来说明先行词所发生的地点和时间,因此关系副词首先是起连接主从句的作用,其次在定语从句中作地点或时间状语.
where的语法功能相当于in (on,at,from...)＋地点名词或表地点的副词there,here等.
when的语法功能相当于in(on,at,from...)＋时间名词或表时间的副词.
例：①As a child ,he used to work hard and help his father on the small farm where he lived.(where ＝on the small farm) 当他还是一个小孩的时候,他就习惯了艰苦的劳动,并帮助他的父亲 在他们所生活的农场干活.
②This is the village where I was born.(where＝in the village) 这就是我出生的村庄.
由when引导的定语从句,其先行词必须是表时间的名词并且在定语从句中作时间状语.
例：①This was a time when there were still slaves in the U.S.A..这是一个在美国仍处在奴隶制度的时代.when=at that time在从句中作时间状语.
②I’ll never forget the day when I left for college with my father.我永远不会忘记我和父亲动身去大学的那天.when＝on that day
why引导的定语从句主要用来限定reason的内容,其表语才是说明原因.
例：①This is the reason why I did so .这就是我要这么做的理由.
why ＝ for which...
②The reason why he succeeded in the exam is that he worked very hard.他这次考试成功的原因是因为他学习非常努力.
说明：在time作先行词表示“次数”时,如被序数词修饰或the last修饰时,只能用that为引导词.
例：①This is the last time(that) I shall go there with you.这将是我最后一次和你一块到那里去.
②The first time (that) I saw you was last month.我第一次与你见面是在上个月.