The weather is so ____high up in the mountains that the forecast is sometimes not reliable.(change)
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These ____can monitor speed and distance from the car in front.(sense)
The director of ____for the bank was very busy organizing interviews and career fairs at various universities during the hiring season.(recruit)
把（）定向移动的方向规定为电流的方向。
A. 电子
B. 正电荷
C. 负电荷
D. 光子
在金属导体中，电流的方向与自由电子实际定向移动的方向（）。
A. 相同
B. 相反
C. 不一定
D. 不相关
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