【单选题】Switchboards may be of the dead-front type in which all __________are installed behind the panels and only the operating handles and instruments are on the front.
【单选题】Switchboards may be of the dead-front type in which all live parts are installed behind _____ and only the operation handles and instruments are on the front.
【单选题】switchboards may be of the dead-front type in which all live parts are installed behind ____ and only the operation handles and instruments are on the front.