交通已成为空气污染的代名词，许多国家打算在未来20年内禁止销售新的汽油和柴油车。
Traffic has become synonymous with air pollution, and many countries intend to ban the sale of new petrol and diesel cars in the next two decades.
由于汽车被禁止使用，交通依赖于电车或轻便马车。
Cars are prohibited, so transportation is by electric cart or by horse and buggy.
这些逐渐变大的规模让全球交通规划者很头痛，他们无法做出决定：是鼓励这种绿色环保的交通方式还是出于安全考虑而禁止。
These larger models are causing headaches for global transportation planners. They cannot decide whether to embrace them as a green form of transportation, or ban them as a safety hazard.
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