The cover of the thermos can't be unscrewed. We can put it in hot water to make the air in the bottle expand by heating. In this way, it will be easier to take it out and screw it out. Or we can put the thermos in the microwave oven and heat it for a while. After it is taken out, it will be easier to unscrew it. However, when heating, we should control the time to avoid corruption. We all know how to unscrew the lid of the thermos. After burning the hot water, if you don't drink it in time, it will soon become cold. It is said that many people pour the hot water into the thermos after burning the water, but sometimes the lid can't be opened.
The reason why the thermos lid can't be unscrewed is mainly because the air inside is hot, but then it gets cold and the gas shrinks, so that the air pressure inside is far less than the atmospheric pressure outside. In this way, it will be more difficult to unscrewe. There is no way to unscrewe it with simple force.
Generally, you can put the thermos bottle in hot water to make the air in the bottle expand by heating. In this way, it will be easier to take it out and screw it out. Or you can put the thermos in the microwave oven for heating, but you should grasp the time to avoid the phenomenon of * * *.