Which of the following devices is common to both mechanical and hydraulic governors?（）
Which of the following devices is common to both mechanical and hydraulic governors?（）
Which of the following devices is a common basic element with nearly all mechanical governors?（）
Which of the following devices is a common basic element with nearly all mechanical governors?（）
Who used compasses frequently as navigators in the eleventh century? A: Scientists B: Governors C: Fortune tellers D: Voyagers
Who used compasses frequently as navigators in the eleventh century? A: Scientists B: Governors C: Fortune tellers D: Voyagers
When the prime movers of two paralleled generators are equipped with mechanical- hydraulic governors， and are operating within their designed range， the unit with the least amount of speed droop will （）.
When the prime movers of two paralleled generators are equipped with mechanical- hydraulic governors， and are operating within their designed range， the unit with the least amount of speed droop will （）.
Among all the elected political officials, only _____ are elected by all citizens of the United States. A: presidents B: congressmen C: vice presidents D: state governors
Among all the elected political officials, only _____ are elected by all citizens of the United States. A: presidents B: congressmen C: vice presidents D: state governors
Under the U.S. system, which of the following is true? A: The president appoints state governors B: The national congress controls the state congresses C: State laws can violate national laws D: Each state should abide by the U.S. constitution
Under the U.S. system, which of the following is true? A: The president appoints state governors B: The national congress controls the state congresses C: State laws can violate national laws D: Each state should abide by the U.S. constitution