单项选择题
A.≤3mg/LB.≤4mg/LC.≤0.15mg/LD.≤1.5mg/L
A.0.1~0.3g/lB.0.1~0.3mg/lC.2~6g/lD.2~6mg/l
A.1.25~1.35g/mlB.1.2~1.3g/mlC.1.25~1.4g/mlD.1.3~1.4g/ml