臭氧是氧气与紫外线发生化学反应而产生的。

Ozone is produced by the reaction between oxygen and ultraviolet light.

《柯林斯英汉双解大词典》

一棵大树每年可以产生大约100公斤的氧气。

A large tree might make around 100kg of O2 per year.

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为了调和这两个事实，科学家们假设，几乎所有产生的氧气都被地球表面的铁吸收了。

As a way of reconciling these two facts, scientists have hypothesized that nearly all of the oxygen being produced was taken up by iron on Earth's surface.

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