听对话,回答问题。 1. Why is David so fat? A. Because he doesn't exercise. B. Because he eats too much at lunchtime. C. Because he watches TV all day. 2 What do we know about David? A. He has too much for lunch. B. He is busy but always does exercise. C. He works all day for many hours. 3. What must David do to keep strong? A. Work hard all day. B. Play basketball. C. Do exercise in the morning and evening.