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Yes, if the inside is bigger than the outside, the milk will be ejected; if the inside is smaller than the outside, the milk carton will be compressed and deformed. The specific reason is that the internal atmospheric pressure and the external atmospheric pressure can be imagined as two hands, and the internal hand and the external hand push each other hard. When the internal air pressure is high, it is equivalent to the strength of the internal hand, which will "push" the milk out. On the other hand, if the external hand is strong, the milk box will be pressed down.