Tweedledum and Tweedledee were standing under a tree, each with an arm round the other’s neck. Last time Alice met them she knew immediately which was which, because one of them had “DUM” embroidered on his collar, and the other “DEE”. ‘No embroidery this time,’ she said to herself. ‘How do I distinguish them?’. ‘O, yes!’, she suddenly remembered that one of them always tells the truth, while the other always lies. ‘I have to ask one of them just one question, he will answer ‘yes’ or ‘no’, and I will know which is which’, she thought. What question was Alice going to ask?