检查所有分接头的变压化，应在分接开关引线拆装后或更换绕组后或必要时进行。
参考答案：对
My knowledge of Hong Kong came only from some movies: a______ of criminals are pursued by the police in the narrow streets and then they have a fight.
A．group
B．team
C．class
D．gang
在实数范围内分解因式a4-14a2+49=______．
