2020托福听力练习：资源回收是否真的有效（下载）

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　　At Brooklyn's recycling depot, discarded metal and plastic gets bulldozed into a large mound.

　　The stuff is then scooped onto the first of a series of rising conveyor belts, from which the trash is sorted through means both mechanical and manual.

　　All that effort produces a variety of salable products, from metals to paper fibers.

　　But is it worth it?

　　In the case of an aluminum can the answer is an unqualified yes.

　　Such a can can be recycled endlessly with no loss of quality.

　　And recycling a can uses less than five percent of the energy that it takes to refine bauxite ore into fresh aluminum.

　　Recycling is worth it when it comes to all metals, though we're better at recycling aluminum than say neodymium.

　　In principle it could work for plastic, too.

　　But because plastic is made from petrochemicals, low oil prices can make it cheaper to just dump old plastic and manufacture new.

　　And plastics degrade as they're recycled, as does paper.

　　That said, a simple cost-benefit analysis does not correctly measure the environmental costs of dumping plastics or cutting down more trees for paper products.

　　The EPA suggests that recycling in the U.S.reduces the same amount of greenhouse gas pollution as taking more than 38 million cars off the road.

　　The sound of recycling may prove music to the ears of future generations.