疑问副词用来问特殊疑问句（特殊疑问词加一般疑问句?）
关系副词引导定语从句.
关系副词：
when引导定语从句,表示时间,其先行词往往是表示时间的名词（如：time,day,hour,year等）．
eg.October 1,1949 was the day when the People's Republic of China was founded.(when表示时间)
where引导定语从句,表示地点,其先行词往往是表示地点的名词(如：place,room,house,street,area等)．
eg.This is the place where my mother was born.(where表示地点)
why引导定语从句,表示原因,常用在先行词reason后面．
eg.I don't know the reason why she looks unhappy today.(why 表示原因)