单项选择题
All of the following operating characteristics are listed on the name-plates of motors used aboard ship except the（）
A.temperature rise B.input kilowatts C.horsepower D.operating voltage
单项选择题 When would you ground an electric hand tool?（）
单项选择题 The load between two steam-driven alternators operating in parallel may be adjusted by varying （）
单项选择题 The purpose of the commutator and brushes on a DC generator is to（）
