The classrooms in the teaching building are all open, and there are elective courses on weekends. As long as the doorman doesn't stop you, you will be fine. There must be no place to store schoolbags in the classroom. The library can, but only temporarily. And there are few seats, so it is difficult to find a seat. You need to exchange your student ID card for the key to the box. You can't store your bag without a card.