进入煤气区域作业应携带CO检测器、二人以上方可进行,并由上风向进入并保持一定的目视间隔距离。
参考答案:对
On returning from work, _____.
A.John found a letter in the mailbox
B.a letter was found in the mailbox
C.a letter was in the mailbox
D.the mailbox had a letter in it
凡上道进行设备检查时,必须设置()
A.减速信号
B.现场防护员;
C.停车信号;
D.作业标。