单项选择题
A ground can be defined as an electrical connection between the wiring of a motor and its（）.
A.shunt field B.circuit breaker C.metal framework D.inter-pole
单项选择题 Brushless generators are designed to operate without the use of（）.
单项选择题 It （） for an emergency generator to require paralleling.
单项选择题 Usually the panels are interlocked with （） so that the devices can be made dead before the doors are opened.
