1.fossil fuels
2.living organisms
3.renewable energy source
4.carbon neutral
5.carbon dioxide
6.toxic chemicals
7.acid rain
8.natural habitat
9.plant material
10.animal fats
11.air pollution
12.natural resources
1.fossil fuels
2.living organisms
3.renewable energy source
4.carbon neutral
5.carbon dioxide
6.toxic chemicals
7.acid rain
8.natural habitat
9.plant material
10.animal fats
11.air pollution
12.natural resources