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

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

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

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

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

A salinity indicator is used to determine the （）.

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

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

The usual symptoms of cavitation in a centrifugal pump is （）.

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