Now, many primary schools and middle schools are recycling textbooks. In my opinion, it's necessary.

现在，许多小学和中学都回收课本。在我看来，这是有必要的。

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The pressure swing adsorption (PSA) is one of the primary methods of treating and recycling volatile organic compound (VOC).

变压吸附为目前处理回收挥发性有机化合物的主要方法之一。

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Modren aluminum industry consists of primary aluminum industry and recycling aluminum industry.

现代铝工业由原生铝工业和再生铝工业组成。

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Traditionally people have believed that a lot of energy within the ecosystem is dependent on primary production of phytoplankton but we believe recycling has a strong input.

BBC: The model should aid future management of the North Sea