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

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

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

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

The temperature differential occurring between the inlet temperature of the fluid to be cooled and the outlet temperature of the cooling medium in a shell-and-tube heat exchanger is greatest in which of the flow designs listed?（）

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

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

Low compressor head pressure in a refrigeration system can be caused by（）.

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

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