大小单双三期必中

简介：There are a total of nine inner and outer seven imperial cities outside the city of Beijing, with twenty city gates from the inside to the outside. Among them, the seven gates in the outer city are Dongbian Gate and Guangqu Gate on the east wall; Zuo'an Gate, Yongding Gate and You'an Gate on the south wall; Guang'an Gate and Xibian Gate on the west wall.