泵控型液压随动舵机控制系统的反馈信号发送器一般由（）带动。
A．三位四通换向阀
B．舵柄
C．舵机房的遥控伺服机构
D．B或C
参考答案：D
Liu Xiang can't attend the Political Consultative Conferences ____ in Beijing due to training. [ ]
A. to hold
B. held
C. to be held
D. being held
采用路灯时间控制器后，路灯可以实现自动（）功能。
A、开关
B、开
C、光
D、遥控
