In New York, pavements (not motor lanes!) are covered with steel bars before asphalt is laid; teeth are wrapped in steel sheets to protect them from bumping into their objects; libraries are built in the niche of tall buildings, with one of the world's largest forest parks; and the world's largest subway network density can achieve the same-floor transfer, car warning. The card reminds people to observe suspects and objects keenly in order to safeguard urban safety. It's amazing that Americans can already coexist hardness and resilience, vitality and strength.