边长为4cm的正方形ABCD绕它的顶点A旋转180°,顶点B所经过的路线长为____ cm.
________ soccer in the street. It's too dangerous.
A. Let me see. I think it's a toilet for a pet(宠物).
B. Yes. I do. I like studying them.
C. Do you know anything about the public signs?
D. OK. What does that sign on the door mean?