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

A pressure drop through the refrigerant liquid line may cause （）.

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

A salinity indicator is used to determine the （）.

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

An increasing head pressure in a refrigeration system, without any corresponding change in the cooling water inlet temperature, would probably be caused by （）.

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

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

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

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