应该是这样说,whether有两个用法,
一个是：是否,he asked me whether i enjoy my work or not.
另一个是：无论,不管, i'll go whether you come with me or not.
容易理解成条件状语从句,可能是因为whether有与if相同的用法,在直接引语边间接引语是要加的间接引语开头的连词,好吧!来个例子：
直接引语： she asked ,"are you sure your father will come?"
间接引语1、 she asked if i was sure my father would go.
2、she asked whether i was sure my father would go.
【但是要注意引导间接地时候句子中出现or not,就一定要用whether 不能用if 了】
P.S. 关于让步状语从句,我也来解释一下,所谓的“让步”也就是退一步说的意思.让步状语从句一般是用though\although\even\if（即使）\however（无论如何）来引导.
例子：although he is in poor health , he works hard(虽然他身体不好,但是工作努力）
even if it rains cats and dogs, i'll go.（即使下倾盆大雨,我也要去）
以上为在下愚见,详情请参照语法书!
