单项选择题 Some large A-Cmotors are equipped with heatersThese could be （） (1)resistance heaters bolted directly to the frame (2)low voltage windings embedded in the motor windings

单项选择题 In order to change the direction of rotation of a D-Cmotor （） (1) the field leads must be changed (2) the input leads must be changed

单项选择题 If a small electric motor is immersed in salt water it should be （） (1) washed in fresh water (2) dried in an oven