The major source of chemical contaminants in hydraulic fluid is （）.

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

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Which of the listed pumps is NOT a positive displacement pump?（）

A.Centrifugal
B.Reciprocating
C.Gear
D.Rotary

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