单项选择题
The refrigeration system low pressure cutout switch is actuated by （）.
A.an electric system manager B.a sensing bulb at the tail coil of the evaporator C.pressure changes in the suction line D.failure of the king solenoid valve
单项选择题 Hydraulic machinery failures are commonly caused by contamination of the hydraulic fluid and （）.
单项选择题 When you adjust a thermostatic expansion valve, （）.
单项选择题 If a centrifugal pump were continually operated with the discharge valve closed, the （）.
