单项选择题
A.< 500mg/LB.1500~1000mg/LC.2000~1500mg/LD.2500~2000mg/L
A.60~100mg/LB.30~60mg/LC.15~30mgD.10~15mg
A.硫化物、沼气B.有机酸C.铁铜等重金属D.A、B 和C