A:禅让制
B:分封制
C:世袭制
D:郡县制
如图,将边长为6的正三角形纸片ABC按如下顺序进行两次折叠,展平后,得折痕AD,BE(如图①),点O为其交点.
My room is a mess, but I __________clean it before I go out tonight. I can do it in the morning.
39之后的奇数是____