石油的组分及各组分的含量都发生了变化：其中一些沸点较高的烃类都降解成了沸点较低的低碳烃类。

And the components and content of oil have all changed: some of hydrocarbons with the higher boiling point are degraded into low-carbon hydrocarbons with low boiling point.

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比如，从沸点较低的组分生产石油产品，就会自动产生一定数量的高沸点产品。

For example, the manufacture of products from the lower boiling portion of petroleum automatically produces a certain amount of higher boiling components.

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该公司称这种轮胎可谓极为环保，其组分的80%都是从非石油原料中提取的。

The company says its tyres are among the greenest produced, with 80% of their ingredients derived from sources other than petroleum.

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