单项选择题
A.insufficient lube oil circulating through the system
B.excessive circulation of lube oil through the system
C.insufficient refrigerant in the system
D.an overworked compressor
单项选择题 Operating a rotary pump at speeds in excess of design requirements could cause（）.
单项选择题 A refrigeration system compressor crankcase is sweating or unusually coldThis is an indication of（）.
单项选择题 When the desired rudder angle is attained by a typical double mm electro-hydraulic steering gear,the（）.