Bicycles are no longer the primary means of transportation in Beijing, a city where rising incomes have meant many commuters can afford to upgrade to cars.

自行车已经不是北京的主要交通工具了，这个城市里的人们随着收入的提高很多已经升级到汽车代步了。

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Roman roads fell into disrepair and disuse during the Middle Age when the primary means of long-distance transportation were walking, horseback riding, or ox riding.

中世纪期间，主要的长途运输工具是：步行、骑马，或骑牛，因此，罗马的道路失修而被废弃。

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The rapid development in science and technology today to solve the transportation demand management is increasingly becoming the primary means of urban transport problems.

在科技迅猛发展的今天，交通需求管理日益成为解决城市交通问题的主要手段。

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So it was the primary means of public transportation

所以它是这里最初的主要公共交通工具，

旧金山的公共交通 - SpeakingMax英语口语达人