小丽非常喜欢学习化学，请你和小丽一起体会活用化学知识的快乐。
（1）小丽放学一进家门就闻到了饭菜的香味，这证实了分子____ 。
（2）小丽在帮妈妈洗碗时，加入少量的洗洁精，很容易就把油乎乎的菜盘洗干净了，其原因是洗洁精具有____ 功能。
（3）妈妈给小丽买的加钙牛奶中的“钙”是指____（填“元素”或“分子”）。

  Rick and Mary are from America．Now they are working in Tianjin．They can speak a little Chinese．Every morning they get up very early．Then they go to work by car.·They are very busy．They have lunch at the factory．①After lunch they work again．They finish their work very late．  In the evening they take Chinese lessons(上汉语课)．They want to talk with Chinese people．They often say，“Chinese people are very friendly(友好的)．”②They like to stay in China and they like to work with Chinese people．

根据短文内容，完成下列题目。

在一个不透明的不带中，红色、黑色、白色的乒乓球共有20个，除颜色外，形状、大小、质地等完全相同．小明通过多次摸球实验后发现其中投到红色、黑色球的频率稳定在5%和15%，则口袋中白色球的个数很可能是（　　）