2020-2021学年英语周报九年级新目标第18期答案及试题（第

2020-2021学年英语周报九年级新目标第18期答案及试题（第十八期），将发布在下图中，扫码即可查看！

When you work out a carbon footprint(碳足迹)，a lot of factors are taken into consideration. For example, driving to the grocery store bums a certain amount of fuel, and fossil fuels are the primary sources of greenhouse gases. But that grocery store is powered by electricity, and its employees probably drive to work, so the store has its own carbon footprint. In addition, the products that the store sells were all shipped there, so that must also be factored into the total carbon footprint. Beyond that, the fruits. Vegetables, and meats that the store sells were all grown or raised on farms-a process that produces methane(甲烷)，which has a greenhouse effect 25 times greater than CO. All of those elements must be combined to understand the full carbon footprint of a given activity.

Although adding up one's own carbon footprint can be difficult, online calculators can do some of the work for you,giving a rough estimate(估算)of your carbon footprint based on the size of your household, the efficiency of your machines, how much you drive or fly, what you eat, and how much you recycle

This isn't perfect, but it is a good way to measure your activities so you can know roughly how much CO2 they produce and take steps to reduce your carbon footprint.