Across
- 4. plants that have no roots, stems, or leaves and grow in water
- 5. an official rule that controls the way that things are done
- 6. the proces of changing into gas or steam
- 8. the type of weather that a country or region has
- 9. microorganisms consisting of a single cell
- 13. solid waste from farm animals
- 14. something that could be dangerous
- 15. a common small insect with wings
- 16. a process in which a substance is put on something
- 17. firm and hard
- 18. the useless materials, or substances left after you use something
Down
- 1. an artificial pool for waste water
- 2. a substance such as air that is neither a solid nor a liquid
- 3. a natural or chemical substance added to soil to help plants grow
- 7. a substance that is harmful to the environment
- 9. to put animal's dead body in the ground
- 10. a mixture of decaying plants and vegetables
- 11. a poisonous gas with a strong unpleasant smell
- 12. connected with, produced by, or obtained from living things
- 19. farm animals