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

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

Which of the listed pumps is NOT a positive displacement pump?（）

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

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

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

Heavy wear in a particular area of the inner circumference of a packing ring may be caused by （）.

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

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

If the head pressure of a reciprocating refrigeration compressor is excessive, （）.