单选题Air entering an air-cooled refrigeration system is indicated by ().Afrosting of the liquid lineBhigher than normal head pressureCa clear sight glassDabnormally cold reefer boxes

单选题
Air entering an air-cooled refrigeration system is indicated by ().
A

frosting of the liquid line

B

higher than normal head pressure

C

a clear sight glass

D

abnormally cold reefer boxes


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