Which of the following statements represents the advantage of rotary pumps as compared to reciprocating pumps?（）
- AThe high discharge pressure of the rotary pumps permits a larger volume of fluid per unit time than the reciprocating pump
- BRotary pumps are capable of pumping more fluid than reciprocating pumps of the same weight
- CRotary pumps occupy only one-half the space of reciprocating pumps
- DRotary pumps eliminate discharge slippage of the pumped liquid, while this does not hold true for a reciprocating pum