>Today foods travel thousands of miles from farms to consumers.  Why? Is it a positive or negative trend?

结构定位四段3-6-6-3，共装配18句话自圆其说。中文思维不损英文写作。汉文心图大纲小笔记，吹牛要打简单的草稿，以防跑题。

起：食物远途运输，对经济有利，对环保有害。

承：市场经济而言，好处多多，皆大欢喜。

转：自然环保而言，坏在燃料污染，地球升温。

合：好坏难以定论，消费者来决定支持土产食物。

The food travel debate is inevitably intertwined between economic interests and environmental concerns.  While food is traveling because transport has become so cheap in a world of globalization, the manner by which food is being carried is not doing the natural environment any favors.  The question is whether to meet human food demand or to reduce pollution?

Linking food with transportation is big business.  The ability to transport food cheaply has given rise to booming business regarding freight by land, sea and air.  As the population continues to grow, so does the demand for food.  Nowadays, all kinds of food may be carried long distances from producing regions to consumer markets in a matter of weeks, days or even hours.  Such is a win-win trade practice, benefitting both sellers who can help create more valuable jobs and buyers who can help supply consumers with more food varieties at more affordable prices.  At this point, commercial globalization seems to be positive at its best, justifying in part why foods need to travel thousands of miles.

Of course, the negative side is about pollution.  Despite the fact that buying and selling foods beyond borders may bolster economic relationships, the environmental impact of transportation is just too great to ignore.  Big trucks, huge ships and giant airplanes that are used to carry foods use fossil fuels.  Fuel burning has become so excessive that environmentalists behind a green cloak are calling on policy makers to effectively reduce pollution, or else. The warning is certainly not groundless, considering that pollution from transportation accounts for no small a part of those emissions which are believed to generate greenhouse effects that eventually cause the Earth's climate to change.  Obviously, the longer the distance food travels, the fuel consumption of the transportation vessels will also be greater, and no doubt the more serious the global warming.  

In view of both the positive side and negative side about long-distance food transportation, there seems no easy answer to the question.  Nevertheless, it is up to consumers to make choices, knowing where food comes from.  Buying local produce not only supports local farmers but also provides dinner tables with the freshest and most nutrient-packed options.