Jack was ten years old and he was a very lazy boy. He didn't like doing any work. He had to go to school, of course, but he didn't study hard there and tried to do little work. His father and mother were both doctors and they hoped that their son would become a doctor, when he grew up. But one day Jack said to his mother, “When I finish school, I want to be a cleaner.” “A cleaner?” his mother asked. She was very surprised, “That's not a good job. Why do you want to become a cleaner?” “Because I would only have to work one day a week,” Jack answered at once. “Only one day a week?” his mother said. “What do you mean? And how do you know it?” “Well,” Jack answered, “I know that the cleaners come to work on Thursday every week. Because I can only see them on that day.” And then his mother laughed and said, “The cleaners go to work on Monday, Tuesday, Wednesday and Friday in other streets.”