Profit from it. Everyday practice is a learning APP for primary and secondary schools. Created by a group of learning gods from Tsinghua and Peking University in Lele classroom, they taught each other learning secrets, covering primary school Chinese, mathematics, Olympiad and extended courses, Journey to the West, Water Margin and Romance of the Three Kingdoms, junior high school English, mathematics, physics, chemistry, biology and senior high school Chinese, mathematics, physics and chemistry. There are a large number of people using the app, and developers want to profit from it, so it is not free, so they start to use it for a fee.