依靠压力比泵压力更高的工作流体的能量来抽送液体介质的是（）。
A．滑片泵
B．水锤泵
C．内燃泵
D．喷射泵
参考答案：D
"Mr Zhu, you'd better _______ too much meat. You're already over weight." said the doctor. [ ]
A. not to eat
B. not eat
C. eat
D. to eat
装设熔断器主要是对电气设备设置（）保护。
A.过负荷
B.断相
C.短路
D.接地
