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

On tank vessels equipped with power operated cargo tank valves, the type of power operator most commonly used is （）.

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

The control mode in which the final control element is moved from one of two flexed positions to the other is known as （）.

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 （）.

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

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

Thermostatic expansion valves can be adjusted for （）.

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