网络上的选课系统，用户可先完成用户的注册登录修改自己的资料，并且登陆以后选择各种各样的书籍，结束日期，归还日期等等(In the network selection system, users can first complete the user's registration and login to modify their own data, and then choose a variety of books, the end date, the return date, and so