单项选择题
A.a centrifugal fan B.a direct expansion cooler C.a hermetic compressor D.a centrifugal pump
With ducted air conditioning systems, the modern tenden...
单项选择题With ducted air conditioning systems, the modern tendency is to use（）
A.central air conditioning system B.high velocity system C.low velocity system D.single duct system
The（） only allows for adjustment of temperature in each...
单项选择题The（） only allows for adjustment of temperature in each room by the occupant manually controlling the air volume admitted.
A.central air condition system B.high velocity system C.low velocity system D.single duct system
The volute of centrifugal pump also acts as a diffuser ...
单项选择题The volute of centrifugal pump also acts as a diffuser converting （）into pressure head.
A.mechanical energy B.heat energy C.potential energy D.kinetic head
