Which of the following statements about pump operations is NOT a correct statement?（）
A. In order for a fluid to be pumped, a fluid must be made to flow
B. A substance must be cold in order for it to be pumped
C. The kinetic energy imparted by the pump can be used to force a liquid through a hydraulic system
D. A pump must receive its energy from an external source
微信支付 
支付宝支付