Question

since when have you been travelling

______ have you been travelling?Since I was a boy.
A.Since when B.When C.For when D.How much

Answer 1

I have been travelling since I was a boy.
我的理解,问句应该是：
Since when have you been travelling?
我的理由：
since I was a boy在句是有时间概念的,翻译：“从孩子的时候起”,相当于since the time when I was a boy.