根据首字母提示补全对话
(An old woman is standing at the side of the road, near the traffic l____ . Liu Mei is on her way to the cinema, but she stops. )
Woman: Oh, dear! What shall I do?
Liu Mei: What's the m____ , Granny? Can I help you?
Woman: I'm on my way to see my h____ . He's ill in hospital.
Liu Mei: Which hospital?
Woman: I don't know! The address was on a p____ of paper, but I can't find it now.
Liu Mei: Is it in your pocket? M____ you put it there.
(The woman finds the paper.)
Woman: Could you tell me how I can get to the hospital? I don't k____ the way. Which is the way to the hospital?
Liu Mei: Go down this street until you r____ the second traffic lights. Turn right; at the end of the r____ you'll see the hospital. It'll take you about half an hour.
Woman: Half an hour? That's too l____ ! Is there a bus?
Liu Mei: Yes, the No. 72 bus will take you there. There's a stop right o____ the hospital. I'll go with you.
Woman: How kind you are! Thank you.
，过点C作两条互相垂直的直线
、
，
轴、
轴交于点A、
，设点
是线段
的中点，则点M的轨迹方程为（）