ar,or,ir,ur,er - which one?

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Across
  1. 2. to throw something
  2. 4. someone who helps you when you are sick
  3. 6. a strong suggestion to do something
  4. 7. a chair needs to be this to sit in
  5. 8. you do this when you see something you don't like
  6. 11. can you really eat this kind of soup?
  7. 14. someone who asks for money
  8. 15. we live here
  9. 16. the Sahara is one
  10. 18. after PE you feel this
  11. 21. birds do this
  12. 22. a butterfly does this
  13. 23. good to have this in case of a power cut
  14. 24. he can wake you up
Down
  1. 1. where you keep your money
  2. 3. a circle has this
  3. 5. when a pipe is broken it is this
  4. 7. it has eight legs
  5. 8. someone who likes the sea
  6. 9. Mars is this compared to the moon
  7. 10. your first school
  8. 12. precious jewel found in a clam shell
  9. 13. before second
  10. 17. polo is a type of this
  11. 19. someone who makes clothes
  12. 20. if your eyesight is not so good
  13. 21. a type of tree