You can't. According to the relevant requirements of the library, the library is different from the commercial bookstore, which sells books, while the library is more strict in the custody and preservation of books. In order to prevent books from being contaminated by food residues, the library absolutely forbids eating them. There are some precious books and materials in the library, which need to be preserved for a long time because of poor liquidity. The smell of food residues and sundries will attract rats, cockroaches and various insects, which will do great damage to books.