Bob is a lovely schoolboy. He likes playing football very much. He often plays football with his classmates after school, but he never goes home too late. He usually gets home between 4:30 and 5:30 in the afternoon. One day he comes back home late, so his mother says, ”You come back home late today, Bob!””Yes, we have got a new teacher. He teaches us Maths,” Bob answers. “How is he?”his mother asks. “I don't know. I think I can't believe him.””Why?”his mother says. “In today's Maths class, one moment he says two and three is five. But the next moment he says one and four is five.” Bob answers.