The general purpose of a heat exchanger is to （）.

Which of the problems listed would came the discharge temperature of an R-12 refrigeration compressor to increase?（）

Thermostatic expansion valves can be adjusted for （）.

If the head pressure of a reciprocating refrigeration compressor is excessive, （）.

Low compressor head pressure in a refrigeration system can be caused by（）.

When a refrigeration compressor has developed a high head pressure as a result of a refrigerant overcharge, you should （）.

On tank vessels equipped with power operated cargo tank valves, the type of power operator most commonly used is （）.

If the thermal bulb of an expansion valve is incorrectly placed at the center of the coil instead of the end, it will （）.

The usual symptoms of cavitation in a centrifugal pump is （）.

When the steering gear is in operation, you should （）.