A foreign visitor to London wanted to ride up the escalator at the subway station, but did not do so. Why?
Could you guess the reason is that he saw a sign saying "Dogs must be carried"--and he didn't have a dog! At first, it you may think you don't have all the information needed to arrive at the answers--but persist and you'll solve them all. Don't worry: in case you need some help, there's a clues page!