题目

B     According to the recent survey, only forty percent of children in our school feel happy. Why? Do you know what happiness'means? A lot of money? No homework every day? High marks or anything else? In face, happiness is always around you if you put your heart into it; When you are in trouble at school, your friends will help you;when you study hard at your lessons, your parents are always taking good care of your life and your health ; when you get success, your friends will say congratulations to you;when you do something wrong, people around you will help you to correct it. And when y溶液、胶体和浊液这三种分散系的最本质的区别是（　　）A．是否能透过滤纸B．是否为均一、稳定、透明的外观C．是否会产生丁达尔效应D．分散质粒子直径的大小