Annoying people

You know,there is a kind of behaviour.It is called annoying.You know the characteristic?

-When I asked to ask me any question,he would say "anything that I do not know".Then I gave him an answer,he would say "I knew already".Lame isn't?So hard to talk to this kind of people.They like to talk something in general even actually they have something really specific to ask, then expecting people would understand their specific target question.What should I do to this kind f people?ignore them..yeay!!!