The tram in Beijing is called "Dangdang" because when the tram comes, the driver steps on the copper bell under his foot and makes a "Dangdang" sound to remind pedestrians to avoid, so people call the tram "Dangdang". There is only one car in Beijing, so when there are many people, we should tow an extra car. The bus is so crowded that some people can't squeeze in. They can only stand on the edge of the car with one foot and hold the frame of the tram with both hands. This behavior is dubbed "buying tickets".
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