单项选择题
A.1/2~2/3 B.1/3~2/3 C.1/2~2/5 D.1/3~2/5
A.2000~8000NM3 B.2500~8000NM3 C.3000~8000NM3 D.3500~8000NM3
A.<0.3g/L B.<0.4g/L C.<0.5g/L D.<0.6g/L