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

The rate of heat transfer from a hot region to a cold region is affected most by the （）.

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

The output volume of a positive fixed displacement pump can be changed only by （）.

A salinity indicator is used to determine the （）.

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 （）.

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

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

The major source of chemical contaminants in hydraulic fluid is （）.