单项选择题
A.臭氧B.氯C.二氧化氯D.紫外线
A.0.2mg/L,0.04mg/LB.0.3mg/L,0.05mg/LC.0.4mg/L,0.06mg/LD.0.5mg/L,0.07mg/L
A.峰点前B.峰点后C.折点前D.折点后