The major source of chemical contaminants in hydraulic fluid is （）.

Which of the following problems could cause the high pressure cutout switch to shut down the compressor in a refrigeration system?（）

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

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

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

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

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

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

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?（）

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