A.厚壁無(wú)縫鋼管,無(wú)縫鋼管B.無(wú)縫鋼管,無(wú)縫鋼管C.無(wú)縫鋼管,厚壁無(wú)縫鋼管D.厚壁無(wú)縫鋼管,厚壁無(wú)縫鋼管
A.100mB.1000mC.2000mD.50m
A.50mg/m3B.100mg/m3C.80rag/m3D.120mg/m3