压力较高的气体进入许用压力较低的容器时,在容器的气体进口管路上装设(),使压力较高的气体经过减压后才进入容器内。
A.闸阀
B.减压阀
C.安全阀
D.大小头
参考答案:B
—That must have been a long trip.
—Yeah, it ________ us a whole week to get there.[ ]
A. takes
B. has taken
C. took
D. was taking
在区间或站内线路、道岔上封锁施工作业时,车站行车室设驻站联络员,施工地点设现场防护员。