Which of the following factors will have the greatest effect on the heating load within a conditioned space?（）

A.The high discharge pressure of the rotary pumps permits a larger volume of fluid per unit time than the reciprocating pump
B.Rotary pumps are capable of pumping more fluid than reciprocating pumps of the same weight
C.Rotary pumps occupy only one-half the space of reciprocating pumps
D.Rotary pumps eliminate discharge slippage of the pumped liquid, while this does not hold true for a reciprocating pump

A.misalignment or worn main bearings
B.insufficient cylinder lubrication
C.defective or poorly fitted valves
D.all of the above

A.They make it easier to replace the pump shaft packing
B.They can be economically replaced as they wear out
C.They can be removed when it is necessary to lighten the weight of the pump
D.They increase the strength of the shaft