I can't. Pure milk that has expired for 4 days is easy to breed a large number of pathogenic microorganisms. These pathogenic microorganisms may cause high incidence of intestinal infectious diseases, abdominal distension, diarrhea, abdominal pain and other symptoms after entering the human body. After 4 days' expiration of pure milk, many of its nutrients have been decomposed, and it is basically impossible to supplement nutrition for the body. The produced proteolytic substances are easy to cause allergic reactions, leading to serious consequences such as itchy skin and asthma. So you can't drink it even if it's unopened and expired for 4 days.