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

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

If the suction pressure at the refrigeration compressor is below normal, the cause can be（）.

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

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

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

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

The amount of fluid friction or internal friction inherent in a mineral lubricating oil is reflected as a measure of its （）.

Who is responsible for ensuring that someone is assigned to close the watertight doors in an emergency?（）

A salinity indicator is used to determine the （）.