This would work even if the train on the left is somewhat heavier. So, it is possible for a train engine to pull cars that are more massive. But wait! There’s an even more important factor: A moving train car is rolling, not sliding. The wheel just touches the rail at one point and then rolls on to another point on the wheel. This is the magic of wheels: For the cars being towed, there is no longer any friction with the rails.
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Fortune reached out to Citi, and the company had no further comment.
（相关报道）我曾佩戴7款运动手环参加纽约马拉松，它们全程记录了我的呕吐经历