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

Thermostatic expansion valves can be adjusted for （）.

An internal bypass is provided on some hydraulic system suction strainers to help reduce the possibility of （）.

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

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

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

An excessive charge of refrigerant in an air-cooled refrigeration system can cause （）.

A salinity indicator is used to determine the （）.

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

The usual symptoms of cavitation in a centrifugal pump is （）.