Which publishing house published this? I'm sorry if it's Dongli. It always happens after a long time. But in general, when we buy books, we always give Nietzsche's or haha book covers. Please cover which page when reading and wash your hands as much as possible, because if you keep looking at the old page, it will turn black, but it will be too obvious compared with the new page. If you wash your hands, the problem will not be too serious.