There is a big tree by the roadside. It has been standing there for many years, and the bark is gradually falling off. A small tree was planted next to it. It is young, lush and full of vitality. The big tree and the small tree have gone through countless ups and downs.

Once, Xiaoshu raised his head and saw Grandpa Dashu next to him and said, "Wow! Grandpa is so tall! When will I be able to be so tall? It's okay if I'm not taller. If I'm taller, I'll get gigantism!" "The little tree is very naughty and very sensible. The big tree lovingly stroked the little tree's head and said, "My child, you are still young. I have grown so tall because I usually absorb nutrients from the land. We trees also need to contribute to human beings, allowing human beings to enjoy the cool under the trees." . But we also have to support humans at all times.” The little tree smiled and said, “Then we trees are the ones that contribute to humans?” The big tree sighed and said, “Yes.”

The speaker has no intention, but the listener has intention. I don’t know how many years have passed. The small tree has grown into a big tree. The big trees have also become old trees. But Xiaoshu always remembered his grandfather's words and made up his mind to contribute to mankind.

One day, the little tree happily ran to the big tree and said, "Grandpa, grandpa, let me tell you some good news. I heard that humans are going to transport some of us to the desert. Let's go." The big tree said to the little tree. : "Grandpa is old and useless. Grandpa should not go." The little tree said, "Grandpa is not old, he is still very strong!" The big tree's usual kindness disappeared, and he said to the little tree angrily: " I'm not going. "The little tree said to the big tree without giving up: "Grandpa, didn't you say that we just want to contribute to mankind?" The big tree said angrily: "There is no one in that desert.

12