Uin- bi- and tri- crossword

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Across
  1. 2. two;twice
  2. 5. figure with three sides and three angles
  3. 7. lasting for two years
  4. 8. to make one
  5. 10. pertainiging to three languages
  6. 11. 1,000,000,000
  7. 12. 1,000,000,000,000
  8. 13. a two-winged airplane
  9. 14. a three legged support
  10. 16. pertaining to one language
  11. 18. being three sided
  12. 19. one;single
Down
  1. 1. taking place every two hundred years
  2. 3. a two-footed animal
  3. 4. being one sided
  4. 6. three
  5. 7. of or pertaining to two languages
  6. 8. a one wheeled vehicle
  7. 9. taking place twice a year
  8. 13. to cut something into two parts
  9. 15. an animal writen about in fables
  10. 17. a one-legged support