A、1~5mg/l B、2~5mg/l C、3~6mg/l D、4~6mg/l
A、<10ppm B、<15ppm C、<20ppm D、<25ppm
A、0.1~1.5mg/l B、0.5~1.5mg/l C、0.5~2mg/l D、0.1~2.5mg/l