尝试去增加和扩展这个知识，去理解如何使用CO2或氧化铜来保存食物。

Try to add and extend the knowledge and understand how you can preserve food by doing the CO2 or copper oxide.

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如果我们用CO2的液体等离子体或另外的氧化铜液体等离子体洗涤苹果与未洗涤的苹果比较，会怎么样？

What if we wash the apple in liquid plasma of CO2 and another copper oxide? And the control is an unwashed apple.

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