许多有禁令的城市仍然允许消费者购买纸袋。虽然纸袋很容易回收，但生产和运输需要更多的能源。
Many cities with bans still allow shoppers to purchase paper bags, which are easily recycled but require more energy to produce and transport.
天然气通常和石油在同类型的地方被发现和开采，通过管道很容易输送，但天然气一般并不被视为运输燃料。
Gas, typically found and exploited in the same sort of places as oil, is easily moved around through plumbing but is not, usually, seen as a transportation fuel.
石油是最大的单一能源和替代品，因为高能量且容易运输的燃料太难找寻。
Oil is the biggest single energy source and replacements for the energy-dense, easily transported fuel are hard to find.
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