某热机热力循环中,每1kg工质从高温热源吸取2500kJ热量,向低温热源释放2000kJ热量,该热机动力循环的热效率为()
A.20%
B.40%
C.50%
D.80%
参考答案:A
采用氮气或惰性气体置换后如需进入容器进行修理,则事先必须用()吹扫,待气体分析合格后方可进入。
A.氮气
B.压缩空气
C.惰性气体
How is the quartz heater different from other types of heaters A. It heats only the objects in a room. B. It is lighter in weight. C. It heats the room quicker. D. It is more common.