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很小的时候就听大人们说过,判断一只开水瓶是否保温,只需要把耳朵靠近开水瓶口,会“嗡嗡”作响的便是保温的。一只开水瓶不保温了,要扔掉时拿起来放到耳边一听,里面仍旧“嗡
When I was very young, I heard people say that judging whether a bottle of water is kept warm requires only putting the ear close to the mouth of a boiling water bottle. A pot of water does not keep warm. When it is thrown away, it is put in the ear and it is still