题目

I           early in the morning when I was still a child.       A.am used to get up          B. used get up          C. use to get up                D.used to get up 答案：D如图，将矩形纸片ABCD(AD>DC)的一角沿着过点D的直线折叠，使点A与BC边上的点E重合，折痕交AB于点F.若BE:EC=m:n，则AF:FB=  ▼ .