单项选择题
The load between two steam-driven alternators operating in parallel may be adjusted by varying （）
A.the speed of the alternators B.the field strength of the machines C.the power factor of the alternators D.steam supply to the prime movers
单项选择题 The purpose of the commutator and brushes on a DC generator is to（）
单项选择题 DC generators are classified according to the manner in which（）
单项选择题 A circuit that has one wire in contact with the hull of the ship is a（）
