当机组试机或工作已完成时应先断开所有负载,让机组在无负载的情况下运行()后关闭起动开关使机组停机。
A、1~2min
B、3~4min
C、5~6min
D、3~5min
参考答案:D
— Is ______ here?
— No, Bob and Tom aren't here. [ ]
A. anybody
B. everyone
C. somebody
D. someone
SH/T0248标准规定冷滤点测定试验前应分别用()洗涤连接管、试杯、吸量管和温度计,然后用经过过滤的干燥空气吹干。
A.正庚烷
B.无水乙醇
C.丙酮
D.乙醚