单项选择题
A.maintain liquid refrigerant at the suction of the compressor
B.maintain a preset suction pressure to the compressor
C.start and stop the compressor at preset operating pressures
D.operate at minimum efficiency
单项选择题 The process of boiling seawater in order to separate it into freshwater vapor and brine is usually defined as （）.
单项选择题 In the production of freshwater from seawater through a process of heating and cooling, the cooling phase of production is usually called （）.
单项选择题 The sensing line for the low pressure cutout switch to a refrigeration system is located （）.