单项选择题 Before liquid can flow into a pump, the air in the suction line must be （） sufficiently to cause the liquid to flow into the suction chamber.

单项选择题 Generally speaking, suction heads require to be （） for high speed or large capacities than for low speed or small capacities.

单项选择题 Some of the energy fed into the pump will be dissipated as （） due to mechanical inefficiencies, the remainder will be converted into pressure rise and fluid velocity.