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

If the thermal bulb of an expansion valve is incorrectly placed at the center of the coil instead of the end, it will （）.

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

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

A salinity indicator is used to determine the （）.

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 （）.

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

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

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