crossword

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Across
  1. 3. to find an effective action in order to eliminate some problem
  2. 4. to become better and more important
  3. 6. the upper layer of earth in which plants grow, a black or dark brown material consisting of a mixture of organic remains, clay, and rock particles
  4. 9. all the people as a whole class
  5. 11. able to be repaired
  6. 14. having or showing certainty; sure
  7. 16. necessary
  8. 19. to cause some consequences
  9. 20. a particular fact that affects what happens in the situation
Down
  1. 1. the mixture of gases that surrounds the earth
  2. 2. the process of contamination of our environment with harmful substances
  3. 5. completely remove or get rid of something
  4. 7. a mutual action or influence
  5. 8. to prevent the environment from being harmed or damaged
  6. 10. to organize, to hold
  7. 12. natural world around us(air, water, land, animals and birds)
  8. 13. activity of factories and plants producing different things,goods or energy
  9. 15. extremely big
  10. 17. to remove harmful substances, to make something clean
  11. 18. the relationships between plants, animals, people, their environment and natural balance between them