Smart people ask questions because they have enough confidence that they are smart to expose their ignorance.

Acting like you know everything doesn't come from a place of intelligence - it comes from a place of fear, that the other person knows more than you, that they will judge you, that a "smart person" would know what you don't know. I've forced myself to ask questions many times in meetings when I thought the answer was probably obvious to everyone else - only to discover that others had been wondering the same thing.