单选题If a refrigeration compressor will not start, the reason may be （）.Athe pressure regulating valve is not closingBan excessive lack of refrigerant in the systemCbadly leaking discharge valvesDworn piston rings
单选题
If a refrigeration compressor will not start, the reason may be （）.
A
the pressure regulating valve is not closing
B
an excessive lack of refrigerant in the system
C
badly leaking discharge valves
D
worn piston rings
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