wh questions are open questions, they leave room for a description or opinion, and are more useful in eliciting information.
when you are asking for information about something.
when you are asking about someone's identity.
- ask about possession.
- ask for a reason.
- ask about the way in which something is done.
- ask about the time that something happened or will happen.
- ask questions about place or position.
- when you are asking for information about one of a limited number of things.