单项选择题

Pressure in an operating hydraulic system is developed （）.

A.only by the pump as its primary function
B.by resistance to the fluid flow through the system
C.by the thermal input to the systems fluid
D.solely by the charge applied by the accumulators

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If a large difference exists between the compressor discharge pressure and the pressure corresponding to the existing condensing temperature in a refrigeration system, you should（）.

A.increase the flow of the cooling water through the condenser
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