单项选择题
Electrical circuits are protected against overheating by means of a/an （）.
A.circuit breaker B.amplifier C.diode D.capacitor
单项选择题 Routine maintenance of lead acid batteries should include （）.
单项选择题 Under which of the listed conditions can the engine room retake the throttle control from the bridge（）.
单项选择题 Copper is often used as an electrical conductor because it （）.
