Here is a harder one 
You enter a room with 5 people. One of these people will always say the truth. The other 4 will alternate their answers between telling the truth and lying. If the first answer such person gives was a truth, the next one will be a lie, the answer ofter that a truth again etc. If the first answer was a lie, then the second answer will be a truth, the third a lie etc.
Your challenge: Find out who is the person who always says the truth by asking exactly 2 questions to anyone. You can ask both questions to the same person or ask questions to two different people.
