(来学网)饮用水适宜的氟浓度一般为
  • A.
    (来学网)0.5ppm
  • B.
    (来学网)0.7~1ppm
  • C.
    (来学网)1.0~1.5ppm
  • D.
    (来学网)2.0ppm
  • E.
    (来学网)以上均不是