Li Dong is a schoolboy. He's twelve. He lives in Beijing. He gets up at 6:30. He reads English and Chinese in the morning. He has breakfast at 7:00. In the afternoon, he has three classes. He often does the homework after dinner. Li Dong likes playing football. His mother's hobby is planting flowers. His father is interested in collecting stamps. He often shows the nice stamps to Li Dong and his mum. They like the stamps very much.

分式﹣$\frac{1}{1-x}$可变形为（　　）

读我国东部地区沿107°48′E的地形剖面图，完成下题．

根据下列各幅地图比例尺判断，其中比例尺最大的地图是（    ）