单项选择题
The amount of fluid friction or internal friction inherent in a mineral lubricating oil is reflected as a measure of its （）.
A.specific gravity
B.viscosity
C.S E number
D.hydrolytic stability
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相关考题
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单项选择题
The major source of chemical contaminants in hydraulic fluid is （）.
A.microscopic steel shavings
B.abrasive waste
C.anti-oxidant compounds
D.oxidation by-products -
单项选择题
If the thermal bulb of an expansion valve is incorrectly placed at the center of the coil instead of the end, it will （）.
A.increase the capacity of the coil
B.increase the superheat at the bulb
C.deliver more refrigerant to the coil
D.decrease the capacity of the coil -
单项选择题
Which of the listed pumps is NOT a positive displacement pump?（）
A.Centrifugal
B.Reciprocating
C.Gear
D.Rotary
