n.(护齿的)氟化物
It is a proven fact that fluoride strengthens growing teeth. 氟化物可以强化生长中的牙齿，这是已证明的事实。
Since then, many studies have confirmed the value of fluoride. 从那以后，许多研究都证实了氟化物的价植。
The use of fluri fluoride to protect teeth is common in many parts of the world. 用氟化物来保护牙齿在世界许多地方很普遍。
