The city, _____ in the north of Shanxi, has a history of more than 1400 years. [ ]

A. located

B. to be located

C. being located

D. locating

如图所示，将一根导体棒ab的两端用细导线与灵敏电流计组成一个闭合回路。让导体ab棒水平向左运动时，电流计的指针向右偏转；导体棒ab水平向右运动时电流计的指针向左偏转，说明感应电流的方向____________ 与有关。让导体棒ab沿竖直方向上下运动时，电路中______ 感应电流产生。