單項(xiàng)選擇題

The （） compressor and its electrical motor are entirely housed in a gas-tight casing.

A.open-type
B.hermetic
C.A and B
D.None of the above

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單項(xiàng)選擇題

In a compression refrigeration plant the refrigerant flows from the expansion valve and through the （） where it absorbs heat from the space being cooled and becomes a gas or vapor.

A.compressor
B.condenser
C.throttle valve
D.evaporator

單項(xiàng)選擇題

Since heat will not flow freely from a body at a （） temperature to another at a （） temperature, it is necessary to expend mechanical work, heat, or electrical energy from an external source to achieve refrigeration.

A.lower；higher
B.shallower；deeper
C.larger；smaller
D.higher；lower