气控液型控制装置的工作过程可分为（）等。

A、液压能源的制备

B、液压油的调节与其流动方向的控制

C、气压遥控

D、系统压力油最大排量控制

Don't argue with him any longer. You are only wasting your breath ______ to win him over to your side.

A．having tried

B．to try

C．to be tried

D．trying