单项选择题
A.freezing the expansion valve closed B.corrosion of system piping C.improper temperature regulation D.all of the above
When the propeller blades are integral with the hub, th...
单项选择题When the propeller blades are integral with the hub, the propeller is called a （）.
A.built up propeller B.solid propeller C.controllable pitch propeller D.suction back propeller
The tendency of a flammable liquid to vaporize is indic...
单项选择题The tendency of a flammable liquid to vaporize is indicated by its （）.
A.ignition temperature B.flash point C.flammable range D.convection index
Moisture in the refrigerant may （）.A.freeze on the expa...
单项选择题Moisture in the refrigerant may （）.
A.freeze on the expansion valve seat and reduce the flow of liquid refrigerant B.emulsify the oil in the condenser C.freeze in the king valve D.clog the oil trap
