如图所示,矩形线框abcd,ab=L1,bc=L2,线框总电阻为r,ad间接电阻R,并串入电流表,以ad边为轴,线框以角速度ω在磁感应强度为B的匀强磁场中匀速转动.求:
Teaching in a village is good for me.
下列哪一种行为不属于先天性行为 ( )