A、When he goes for a walk. B、When he drives the car. C、When he passes somebody. D、When he chats with Peter. D

Peter’s uncle lived in the country. Once Peter went to stay with him for a few weeks. Whenever they went for a walk or for a drive in the car and they passed somebody, his uncle waved. Peter was surprised, and said," George, you know everybody here. Where did you meet them all?"
    "I don’t know all these people, "said his uncle.
    "Then why do you wave to them?" asked Peter.
    "Well , Peter, "answered his uncle," When I wave to someone and he knows me, he is pleased. He continues his journey with a happier heart. But when ! wave to someone and he doesn’t know me, he is surprised and says to himself, ’ Who is that man? Why did he wave to me?’ So he has something to think about during the rest of his journey, and it makes his journey seem shorter. So I make everybody happy."