听力原文:M: How come David is always so full of energy? W: He has a strange but highly effective way of sleeping. M: What is that? W: He takes a short sleep for an hour every six hours and has a total of four hours of sleep each day. M: Where did he get that strange idea? W: He read flora a book which said it was the best way for human beings, and he believed it. M: How many hours do you sleep a day? W: I need at least seven hours. I once tried to follow David's example, but it never worked out for me. M: If I sleep during the day, I can never wake up. W: Not everyone is a David I guess. How does the man feel about David's way of sleeping?