when i came back from school，水燒開后，在電瓶車上，if you don t believe it，我把這件事告訴了媽媽， 我放學回來時， which is the principle of heat expansion and cold contraction！但是，瓶子就要爆炸了，熱脹冷縮的原理，i told my mother about it. she said that she had never paid attention to this phenomen