(来学网)当水质发黑、发臭时水中溶解氧浓度可
  • A.
    (来学网)大于5-6MG/L
  • B.
    (来学网)小于5-6MG/L
  • C.
    (来学网)大于4-5MG/L
  • D.
    (来学网)小于4-5MG/L
  • E.
    (来学网)小于3MG/L