_____ to know Professor Zhang. [ ]
A. He said
B. I said
C. He is said
D. It says
答案:C
道岔支距,作业验收标准的容许误差为()。
A.1mm
B.2mm
C.4mm
D.6mm
有限空间危害控制措施之一是将作业场所与()有效隔离。
A、外界
B、设备
C、系统
D、以上均不正确