引起氟牙症的水源中含氟浓度是 ( )A.超过0.2ppm,小于0.5ppm B.超过0.1ppm,小于0.5ppm C.低于1ppm,超过0.5ppm

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问题 引起氟牙症的水源中含氟浓度是  (    )

选项 A.超过0.2ppm,小于0.5ppm
B.超过0.1ppm,小于0.5ppm
C.低于1ppm,超过0.5ppm
D.超过2ppm
E.超过1ppm,小于2.0ppm

答案D

解析
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