高速旋转机械启动试运转，（）。
A.可突然提速
B.不可点动
C.应点动
D.应长时间试转
参考答案：C
简述带传动的工作原理和优缺点及用途？
The quality of EGC messages is（）affected by the position of the ship, the time of reception and climatic conditions.
A.sometimes
B.all times
C.never
D.partly
