It is of course necessary to listen carefully in class, but as one of my former teachers said, no one can concentrate in a class, which means it is impossible to concentrate for more than 40 minutes, so there is also a problem of time allocation in class. Teachers can relax when they talk about familiar things. It has to be said that if there are too many students in a class, the teacher's attention will drop a lot. I was studying Shang Xin art in Baohe Wanda. There are eight students in a class. I can communicate with the teacher at any time, and the teacher can also answer questions at any time, which greatly improves the efficiency.