丹东：首座“污水处理桥梁”在建

百度 中国城市人口密度大，行人与机动车相互干扰问题严重，这极大降低了步行的吸引力，从而降低公共交通设施的吸引力，使人们更多选择私人小汽车出行。

Apple and Google have jointly created the ExposureNotification framework to help governments and public health authorities reduce the spread of COVID-19 through contact tracing, with user privacy and security core to the design. Public health authorities can use this framework to create apps that enable users to take measures to protect themselves and help others. Consistent with our privacy principle of transparency, we are publishing reference documentation, detailed specifications, and source code for the ExposureNotification framework.