Erm - it is possible to have more than one question for an answer. e.g. answer is 'a cup of tea'. Question could be: "what was Arthur Dent always asking for" or "What are you drinking at the moment" etc. etc. Xyzzyplugh, I think that it is impossible to know everything - e.g. not every question has an answer due to the Uncertainty Effect. Finding the answer is also the whole point. Why conclude that a question has an answer if you never find it? Erm, I'm off to lie down now .......
Andy