Pitting in the suction areas of a centrifugal pump bronze impeller is usually caused by （）.

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

An excessive charge of refrigerant in an air-cooled refrigeration system can cause （）.

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

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

If you are given the job of adding hydraulic fluid to a mooring winch, and are not certain as to the type of fluid to use, you should （）.

Which of the following statements is correct concerning heat transfer?（）

Thermostatic expansion valves can be adjusted for （）.

If the relief valve on the discharge side of a hydraulic pump lifts, the cause could be （）.

Which of the following problems could cause the high pressure cutout switch to shut down the compressor in a refrigeration system?（）