单项选择题
A.20m B.30m C.50m D.60m
A.20g/m3~1000g/m3 B.30g/m3~2000g/m3 C.30g/m3~3000g/m3
A.5cm B.10cm C.15cm D.20cm
A.水 B.不导电的灭火器材 C.潮湿的黄沙
微信扫一扫,加关注免费搜题