题目

听下面一段对话，回答问题。 （1） Where did Bob meet Anna's brother? A . On his way to school. B . On his way home. C . On the playground. （2） Who is on the school basketball team? A . Anna's brother. B . Anna. C . Bob. （3） What will they do after school? A . Watch a movie. B . Go to a concert. C . Play basketball. 答案：A A B（09年莱阳一中期末文）已知动圆过点，且与直线相切，则动圆圆心的轨迹方程为A．             B．                 C．                 D．