平刨机和圆锯机一般采用电动机通过皮带传动使主轴旋转，电动机皮带轮越大，主轴转速越高。
参考答案：对
--- Driving on icy roads is very dangerous ! The more ice there is, the _______ down the road you have to look. You should be more careful.
--- OK, I will.
A．more far
B．farer
C．farther
D．farthest
三相电路在电源不变的情况下，同一负载由星形连接改为三角形连接时，功率增加到原来的（）倍。
A.1/3
B.1
C.2
D.3
