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

The general purpose of a heat exchanger is to （）.

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

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

If the viscosity of the liquid being transferred remains constant as the discharge pressure increases, the rotary pump （）.

Thermostatic expansion valves can be adjusted for （）.

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

The rate of heat transfer from a hot region to a cold region is affected most by the （）.

A salinity indicator is used to determine the （）.

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