Many scenes in this set of documentaries are touching. For example, the school song of the kindergarten teacher read by Yi Zhongtian's mother: "The simple child, the simple child, the main body of the future world is good or bad. I don't know the benefits, I don't know the benefits; I'm happy to play, I don't care about the wrong. The social value is without me, Without me, benefit the people, first benefit the children.” For example, Professor Zhang Changshao, the fo...