尽管生物物质当它燃烧时，像汽油一样释放碳，但是当植物生长时，它们吸收大气中的二氧化碳，减少了总的碳迹。

Even though biomass releases carbon when it is burned, just like oil, when new plants are growing they absorb carbon dioxide from the atmosphere, reducing the overall carbon footprint.

youdao

危害还不止这些，当汽车和工厂燃烧汽油和煤炭时，一些化学物质释放进入大气层。

There are other dangers. When automobiles and factories burn gasoline and coal, certain chemicals get into the air.

youdao