本质安全型防爆设备或部件的标志是( )。
A．冷却
B．窒息
C．隔离
D．化学抑制
参考答案：A
解析： 本质安全型防爆设备或部件的标志是冷却。
Which of the following statements about the payback period is FALSE（）
A. The payback period provides a rough measure of a project’ s liquidity and risk.
B. The payback period is the number of years it takes to recover the original cost of the investment.
C. The payback method considers all cash flows throughout the entire life of a project.
蒸汽往复泵有（）三大部分。
①蒸汽机
②水泵
③传动部件
④电动机
A.②③④
B.①③④
C.①②③
D.①②③④
