Just take a few shots at the bottom.
Whether it is a plastic cup, a glass cup, a travel mug or a lid of a thermos cup, it is because the air and water inside are inflated after pouring hot water into the cup. After a while, the water temperature is lowered, but It has contracted, which causes a pressure difference inside and outside the cup, so it will not be opened. The key to opening the lid is to overcome the pressure difference.
Method 1: Turn the cup upside down, slap the bottom of the cup a few times, and then screw the lid. If it is not effective, the cup can be placed in hot water so that the water in the stainless steel thermos is warmed up and the volume is expanded (ie, the pressure inside the cup is increased), and it is easy to open. Alternatively, put the cup in the refrigerator, take it out, and then open it with hot water.
Method 2: Use a metal foil to gently squat at the gap between the cup mouth and the lid, and the air is easy to open after entering. Method 3: Gradually tap or use the rubber hoe to get the place where the hot water bottle is sold. They have rubber hoes and opening tips. Like those stainless steel outer casings, they can be handled due to ectopic thread. Handling with a rubber hammer will no longer cause damage, it will just position the thread