what .that.where.which.when.who.whom.的具体用法和区别

what.that.where.which.when.who.whom.为特殊疑问词用来引导特殊疑问句.that.which.who.whom.也是关系代词,在定语从句中为引导词,引导定语从句；where.when.也是关系副词,其在定语从句中作用同关系代词.