edward_george1:
When Zachariah questions Gabriel, he is struck dumb, because he is questioning his metaphysical superior. When Mary asks a question, the angel answers her, because she, being the Immaculately Conceived Queen of the Angels, has the right to ask questions of the Angels.
Or it’s merely becuase of HOW Mary asks the question.
Zechariah says 'How shall I know this?" He’s a priest who surely knows the story of Samson, Isaac, etc.
Mary, on the other hand says, “How will this happen?” This is something unheard of. Of anything Mary is trying to understand, not being unbelieving.