A passenger shows QR code at a metro station in east China's Shanghai, Jan. 16, 2018. Shanghai metro said on Tuesday that it will allow QR code payment through the whole subway network since Jan. 20. Passengers can pay for their tickets via Alipay or China UnionPay simply by scanning the QR code at the entrance and exit after downloading a mobile app called "Metro Daduhui". (Xinhua/Ding Ting)