It's March 12. Li Ming and his classmates are on a hillside. They are planting trees as a school project. A worker is there helping them.
Li Ming: Excuse me, sir. We are digging a hole. Is it big enough?
Worker: Maybe you should make the hole a little bigger. It must be large enough to hold the roots of the seedling.
Li Ming: I see.Thank you.
Worker: Now, put the seedling inside, cover the roots and fill the hole with dirt. Then pack the dirt around the new tree with your feet.
Wang Mei: OK. By the way, there is another group of people down the hill. Are they also coming to plant trees?
Worker: Yes.Many people are worried because the environment is changing, and they want to do something to help.
Li Ming: These changes are serious. When there is a dust storm in spring, it gets windy and dirty everywhere.
Wang Mei: Ms. Liu told us the wind blows the dirt and the sand here from the north. Nothing can stop the wind because there are not many trees left.
Worker: Exactly. A lot of rich lands in the northern area have turned into desert.
Li Ming: I suppose tree planting is very important work.
Wang Mei: For sure. I really like this project. It's also a great way to learn about nature.
Worker: Yes. It's fun and important to plant plants. Oh, and please remember to put a little water in the bottom of the hole.