主轴装置上的调绳离合器可实现（）与主轴脱开，以调节绳长
A、电机
B、盘形闸
C、游动滚筒
D、固定滚筒
参考答案：C
The man is weak in health, and is advised by the doctor ________more exercise.[ ]
A. taking
B. should take
C. took
D. to take
下列行为不属于繁殖行为的是[ ]
A．喜鹊筑巢
B．家鸽求偶
C．麻雀育雏
D．乌鸦集众鸣叫
