单项选择题
A．0.2% B．0.5% C．0.1% D．0.02% E．0.05%
A．水氟＜0.3ppm，氟牙症指数＜0.2 B．水氟＜0.4ppm，氟牙症指数＜0.3 C．水氟＜0.2ppm，氟牙症指数＜0.1 D．水氟＜0.4ppm，氟牙症指数＜0.2 E．水氟＜0.3ppm，氟牙症指数＜0.3
A．多生牙 B．四环素牙 C．融合牙 D．畸形中央尖 E．畸形舌侧窝