One cause of high head pressure occurring in a refrigeration system can be （）.

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

The rate of heat transfer between the hot and cold fluids passing through a shell-and-tube type heat exchanger will （）.

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?（）

A grease gun is generally used to lubricate a （）.

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

An internal bypass is provided on some hydraulic system suction strainers to help reduce the possibility of （）.

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

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