儿子已经四岁半了。我常利用休息时间和他一起玩,一起做科学小实验。一次,我和孩子做“鸡蛋浮起来了”的小实验。我们用玻璃杯装满清水,拿一个鸡蛋放进杯里,只见鸡蛋立即沉入杯底。我让孩子把住食盐一点点地放入杯里,并且用筷子搅动,这时看到鸡蛋慢慢地往上浮,随着盐的增加鸡蛋浮到了水面上。孩子高兴地叫起来:“浮起来了,浮起来了!”我问: My son is four and a half years old. I often use the rest time to play with him, to do a scientific experiment. Once, my child and I did a small experiment of “floating eggs.” We filled the glass with water, took an egg into the cup, and saw the egg immediately sink into the bottom of the cup. I asked the children to put salt in the glass a little bit and stirred them with chopsticks. At this moment, they saw the eggs floating up slowly, and as the salt increased, the eggs floated on the water. The child cried happily: “Float up, float up!” I asked: