星期天,去舅舅家看到上八年级的表妹在鱼缸边看着水中的金鱼发愣,我开玩笑地说:“鱼把你的魂给勾走了吧。”表妹回过头,扮了个鬼脸后,郑重其事地问到:“哥,物理书上说鱼是靠改变自身体积来实现上浮和下沉的,我观察这么半天了,只看到金鱼在游动过程中吐泡泡,鱼怎么改变的自身体积呀?”我告诉她鱼身体里有鱼鳔,它是靠改变鱼鳔里空气的多少来改变自身体积的。当鱼想下沉时,就 Sunday, go to the uncle’s house to see the eighth grade cousin looked at the aquarium fish goldfish in a daze, I jokingly said: “Fish to your soul to hook go.” “Cousin turned back and made a face After solemnly asked: ”brother, the physical book that fish by floating their own volume to achieve the float and sink, I observed so long, only to see the goldfish swimming in the process of spit bubbles, How did the fish change its own volume? “” I told her that there is fish in her body. It changes its volume by changing the amount of air in the fish. When the fish want to sink, it