It is early in the morning, about seven o'clock. Peter is on the bus. He's going to school. There are many people on the bus and it is a bit hot. Peter is sitting by a window with a book in his hands. The bus driver is driving slowly(慢地). Most people on the bus are using their mobile phones. A girl in a red sweater is standing near Peter. She looks very happy. She is reading some funny things on her mobile phone. A fat boy behind him is busy playing games on his mobile phone. A tall man is Jack. He is listening to music on the mobile phone. He's about thirty years old. They are all busy and happy.

学完《我们上路了》，你明白一个什么道理？