(1) Take their question literally, point out minor grammar errors and slight typos, and answer it technically correctly but in such a fashion as to be utterly meaningless
(2) Answer precisely the question they asked, knowing full well that your answer can't possibly help them
(3) Answer their question, figure out what they actually meant to ask, and push them in the right direction gently
Now personally, I do (3). And it takes a little bit of extra effort to realize that when someone asks "how do I use extern on classes" what they *actually* mean is "could you please explain the difference between declarations and definitions, and show me how to solve a circular dependency graph". But, you know, it's worth it.
I don't get why so many people do (1) or (2).