A.15mg/m3(10ppm) B.30mg/m3(20ppm) C.75mg/m3(50ppm) D.150mg/m3(100ppm)
A.0.1 B.0.2 C.0.3 D.0.4
A.氯化鈉 B.硫酸鈉 C.堿式碳酸鋅 D.硫酸鋇