屏幕中央有一个半径为R1的大圆和一个同心的且半径为R2的小圆,同时在大圆和小圆中间均匀分布着12个与大圆和小圆相切的圆-The screen has a radius R1 of the great circle and a concentric radius R2 and the small round, while in the great circle and small round evenly distributed among 12 small round and the great