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 （）.
A.evaporation B.distillation C.dehydration D.condensation
单项选择题 The sensing line for the low pressure cutout switch to a refrigeration system is located （）.
单项选择题 Which of the following statements is true concerning any evaporator?（）
单项选择题 A knocking sound emitted from an unloaded air compressor is probably caused by （）.
