单项选择题
Grease coatings on electrical contact surfaces increase contact resistance and should be removed with a/an （）.
A.small wire brush B.compressed air jet C.clean dry cloth D.10% solution carbon solvent and water
单项选择题 Aboard ship, a grounded field coil in an AC motor can be determined by using a （）.
单项选择题 A generator is prevented from becoming motorized by the use of a/an （）.
单项选择题 Which of the electrical properties listed will always be the same for each component in a parallel circuit?（）
