【简答题】听短文和问题,判断正(T)误(F)。 ( )1. John is a Grade One student. ( )2. Mr Black is taking John to the school. ( )3. John's mother doesn't go to work on Sunday. ( )4. They are going to take the No...
【简答题】已知向量 OA =(2 2 ,0),O是坐标原点,动点 M 满足:| OM + OA |+| OM - OA |=6. (1)求点 M 的轨迹 C 的方程; (2)是否存在直线 l 过 D(0,2)与轨迹 C 交于 P、Q 两点,且以 PQ 为直径的圆过原点,若存在,求出直线 l 的方程;若不存在,说明理由.