单项选择题
A.petroleum crystals B.phosgene gas C.water vapor D.carbon monoxide
In an operating refrigeration system low on refrigerant...
单项选择题In an operating refrigeration system low on refrigerant, a liquid line sight glass will（）
A.be clear B.be blue C.be light green D.show bubbles
The thermal expansion valve reacts directly to the （）A....
单项选择题The thermal expansion valve reacts directly to the （）
A.temperature in the space being cooled B.liquid refrigerant pressure at the solenoid valve C.pressure drop across the evaporator coils D.refrigerant gas superheat at the coil outlet
When transmitted by a reduction gear, diesel engine spe...
单项选择题When transmitted by a reduction gear, diesel engine speed is reduced and the torque available for work （）
A.remains the same B.is reduced C.is increased D.is eliminated
