[简答题]什么是PRA？

If you think you can make the planet better by clever shopping, think again. You might make it worse.
You probably go shopping several times a month, providing yourself with lots of opportunities to express your opinions. If you are worried about the environment, you might buy organic food; if you want to help poor farmers, you can do your bit by buying Fairtrade products; or you can express a dislike of evil multinational companies and rampant globalization by buying only local produce. And the best bit is that shopping, unlike voting, is fun; so you can do good and enjoy yourself at the same time.
Sadly, it’s not that easy. (41) . People who want to make the world a better place cannot do so by shifting their shopping habits: transforming the planet requires duller disciplines, like politics.
Organic food, which is grown without man-made pesticides and fertilisers, is generally assumed to be more environmentally friendly than conventional i
A. The aims of much of the ethical-food movement--to protect the environment, to encourage development and to redress the distortions in global trade--are admirable.
B. By maintaining the price, the Fairtrade system encourages farmers to produce more of these commodities rather than diversifying into other crops and so depresses prices--thus achieving, for most farmers, exactly the opposite of what the initiative is intended to do.
C. Proper free trade would be by far the best way to help,poor farmers. Taxing carbon would price the cost of emissions into the price of goods, and retailers would then have an incentive to source locally if it saved energy.
D. There are good reasons to doubt the claims made about three of the most popular varieties of "ethical" food: organic food, Fairtrade food and local food.
E. But following the "green revolution" of the 1960s greater use of chemical fertiliser has tripled grain yields with very little increase in the area of land under cultivation.
F. And since only a small fraction of the mark-up on Fairtrade foods actually goes to the farmer--most goes to the retailer-the system gives rich consumers an inflated impression of their largesse and makes alleviating poverty seem too easy.
G. Producing lamb in New Zealand and shipping it to Britain uses less energy than producing British lamb, because fanning in New Zealand is less energy-intensive.