Mum: I'm getting something ready for tomorrow. Tomorrow is Tre e-planting Day.  Li Ming: Tree-planting Day? What do people do on this day, Mum?  Mum: Many, many people will go and plant trees.  Li Ming: Why do they do tha t?  Mum: To make the earth more beautiful. And to make our life better.  Li Ming: But I often see people on TV cut down many big trees. Why do they do that, Mum?  Mum: Hm, to make paper, houses, and to make our life better.  Li Ming: To make our life better, too? I just don't understand. Mum, why do many people go and plant trees on the same day?  Mum: Oh, my dear son. It's hard to explain to you. When you grow up, you will understand. Just remember trees are very important to us.  What was said before this conversation?

Li Ming: What are you doing, Mum?