用户注册方可进入用户区，浏览到图书馆的书库，看到最新到的图书，可以根据图书卡号查询已经借了那些书，并可以借书，可以添加新书，删除书，到用户还书的时候可以为其清除所借的书。-Register before entering the user area, browse to the library stacks, to see the latest books, according to the book card check those books have been borrowed and c