The view that questions are 'requests for missing information' is too simple when language use is considered. Formally, utterances are questions when they are syntactically marked as such, or by prosodic marking. Functionally, questions request that certain information is made available in the next conversational turn. But functional and formal questionhood are independent: what is formally a question can be functionally something else, for instance, a statement, a complaint or a request. Conversely, what is functionally a question is often expressed as a statement. Also, verbal signals such...