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

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

Which of the following statements is correct concerning heat transfer?（）

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

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

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

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

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

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?（）