A.易燃 B.易爆 C.易腐蚀管道 D.易中毒
A.5000 B.3000 C.1000
A.经验判断 B.化验分析 C.试纸试验 D.预备检查
A.200mm B.350mm C.500mm
A.17% B.14% C.16%
