Teacher Yan Shushi reads Xiao Fosun (please check the text online. I put the question here)

1, rigorous and meticulous; He never erases a word or symbol, but writes it down, like a nail on a nail or chess left behind (this is my idea, for reference only)

He happened to be at the door of the classroom when the bell rang. His voice is beautiful, flowing like music; The blackboard is extremely neat, and a blackboard makes him write in order, like a well-laid calligraphy, like a game of Go.