A:①②③
B:②①③
C:③①②
D:③②①
(Ⅰ)求动圆圆心P的轨迹方程;
(Ⅱ)过点(1,0)的直线l与曲线P交于A,B两点,若 OA→⋅OB→ =﹣2,求直线l的方程.
The French book must belong to _______, because he studies French.