I just bought one at noon today and I can't open it. I searched a lot on the internet and said that I should pull hard and slowly. But it's not worthwhile if you spill it ~ ~ ~ I tried it and my hand hurts. I thought about it, can it expand with heat and contract with cold? I've opened various bottle caps like this before. So I carefully poured cold water on the bottle cap, wrapped it in a napkin, and miraculously opened it with a slight twist. It was easy, but be careful not to let cold water flow in. Before you dare to do this, you must make sure that the bottle cap is tight.