A.3mg/m3(2ppm) B.30mg/m3(20ppm) C.5.4mg/m3(2ppm) D.2mg/m3(5.4ppm)
A.一級 B.二級 C.三級 D.四級
A.閾限值 B.安全臨界濃度 C.危險臨界濃度 D.30mg/m³(20ppm)