여쭈다 and 여쭤보다 are the humble words for asking, used when the person you ask outranks you, and the clause in front gives your reason for asking. Half of these lines are the same softener, saying you are only asking because you are curious or because you do not know, which takes the edge off the question. The plain word for ask is 묻다; choosing 여쭈다 is about showing respect to the person being asked, not about the question.