单项选择题
A.hydrogen chloride B.calcium chloride C.sulfuric acid D.muriatic acid
A circuit breaker and a fuse have a basic similarity in...
单项选择题A circuit breaker and a fuse have a basic similarity in that they both （）.
A.can be reset to energize the circuit B.should open the circuit when overloaded C.will burn out when an over current flow develops D.All of the above
An electrical device which prevents an action from occu...
单项选择题An electrical device which prevents an action from occurring until all other required conditions are met is called a/an （）.
A.limit B.monitor C.modulator D.interlock
The frequency output of an operating alternator is cont...
单项选择题The frequency output of an operating alternator is controlled by the （）.
A.relative speed of the rotor poles B.number of turns of wire in the armature coil C.strength of the magnets used D.output voltage
