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

Heavy wear in a particular area of the inner circumference of a packing ring may be caused by （）.

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

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

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 （）.

A gradual decrease in the discharge pressure of an operating hydraulic pump can be caused by （）.

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

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

A salinity indicator is used to determine the （）.

If the viscosity of the liquid being transferred remains constant as the discharge pressure increases, the rotary pump （）.