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Whichofthefollowingdevicescanrouteelectricalsignalsonlywhenactivatedbyanexternalcontrolsignal?()A.SolenoidB.RelayC.ClutchD.Capacitor
题目
Whichofthefollowingdevicescanrouteelectricalsignalsonlywhenactivatedbyanexternalcontrolsignal?()
A.Solenoid
B.Relay
C.Clutch
D.Capacitor