风冷热泵型冷水机组的冷凝器属于()换热器。
A.壳管式
B.套管式
C.肋片管式
D.板式
参考答案:C
—Hello! May I speak to Mr Smith?
—________, please. He's answering another call right now. [ ]
A. Go on
B. Come on
C. Keep on
D. Hold on
减压侧线油的馏分范围一般为()。
A、350-500℃
B、400-500℃
C、450-600℃
D、300-500℃