单项选择题
A “dead front” switchboard is one （）.
A.without switches on it B.with insulated switches and no exposed terminals C.without circuit breakers D.without safety hand nails nor rubber mats
单项选择题 The total resistance of a parallel circuit is always （）.
单项选择题 Reduced voltage applied to a motor during the starting period will （）.
单项选择题 Line losses in a distribution circuit are kept to a minimum by （）.
