A young man walks through the forest

Question: A young man walks through the forest. He comes to a bridge. In front of the bridge is a large man carrying an axe. The man says, "If you want to cross this bridge, you must tell me a statement. If I think the statement is true, you will be strangled to death. If I say the statement is false, your head will be chopped off." A few minutes later, the young man walked over the bridge, while the larger man stood pondering. What was the statement the young man had given?

Question: What can be broken but never forgotten?

Question: People see through me, but none pass through without killing me. I can be anywhere, and can be seen double or single. What am I?

Question: Which thing that comes once in a year, twice in a week?

Question: You are trying to get your chicken, fox, and wheat to the barn. However, the barn is on the other side of the river. You are on a boat and can only transport one animal or wheat at a time. You must choose carefully not to leave the wrong two together, though. It's either the fox will eat the chicken or the chicken will eat the wheat. How do you take each thing across safely?

Question: During what month do people sleep the least?