It is true that many colleges and universities have closed the whole campus badly. Foreigners and vehicles need to register, make an appointment and invite letters to enter the school. The classrooms, libraries, football fields, gymnasiums and swimming pools of the school are basically closed to the public, and access cards that are only valid for teachers and students of the school are set up. Of course, this also has its own reasons. The reason why the school does this is for itself. From the security point of view, if the access card is set, outsiders will not be able to enter the dormitory, teaching building, library, gymnasium and other places of the school, which will greatly reduce the probability of school property being stolen.