單項(xiàng)選擇題

The purpose of the commutator and brushes on a DC generator is to（）

A.change AC to DCcurrent
B.change DC to AC current
C.neutralize a armature reaction
D.carry current to the outside circuit

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單項(xiàng)選擇題

DC generators are classified according to the manner in which（）

A.they are used
B.the field windings are connected to the load
C.the armature circuit is connected to the load
D.the field windings are connected to the armature circuit

單項(xiàng)選擇題

A circuit that has one wire in contact with the hull of the ship is a（）

A.series circuit
B.grounded circuit
C.short circuit
D.closed circuit