按照以往的经验，人流量集中的地方，公交枢纽、公交地铁线上，包括天安门广场观看升旗的人群中，都是他们工作的重点地区。
According to the previous experience, the places with massive human traffic, including the public transit hubs, bus and subway lines, and even the crowd watching the flag-raising ceremony in Tiananmen Square, are the key areas in their work.