2/5, 3/7, 4/10, 6/14, 8/20, 12/28, () A.224/56 B.14/32 C.20/48 D.16/40 2/5, 3/7, 4/10, 6/14, 8/20, 12/28, ()A.224/56 B.14/32 C.20/48 D.16/40 参考答案 查看答案