单项选择题
A.0.5m/s B.1m/s C.1.5m/s D.2m/s
A.5min B.10min C.15min D.15min以上
A.50mm B.210mm C.100mm D.250mm
A.管道直径的1/3处 B.管道直径的2/3处 C.管道中心线处 D.不受限制
微信扫一扫,加关注免费搜题
