A.汽-液B.液-液C.汽-汽D.液-固
A.0.6~0.7g/cm3B.0.7~0.8g/cm3C.0.8~0.9g/cm3D.0.9~1.0g/cm3
A.明確的警戒標(biāo)志B.有專人檢查C.有防護(hù)措施