Trains usually have two ________ to convert currents. A: cooling fans B: locomotives C: circuit breakers D: ectifiers

Trains usually have two ________ to convert currents. A: cooling fans B: locomotives C: circuit breakers D: rectifiers

Smaller locomotives transfer the rail cars from the ( ) to a classification yard, where each car is coupled to one of several long distance trains being assermbled there, depending on that car's destination. A: wagons B: sidings C: cars D: goods stations