1. Variety in the number of species of plants and animals.
2. The sending out of poisonous gas when engines burn gasoline.
3. The length of time that a person or an animal lives.
4. The typical weather conditions in an area.
5. The process of clearing forests.
6. A line of sharp rocks near the surface of the sea.
7. The layer of gases that prevents harmful
radiation from the sun from reaching the earth.
8. A long period of dry weather when there is not enough rain.
