Why <y> stays?

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Across
  1. 3. kids often love to play with these
  2. 4. animals that include chimps and lemurs
  3. 6. lots of people think cats are ___ than dogs because of how much they sleep
  4. 7. a baby did this because it was hungry
  5. 8. a favorite activity for kids
  6. 9. what you tell a dog when you want it to keep still
Down
  1. 1. a feeling we get when things are good
  2. 2. most birds and airplanes are known for this
  3. 4. after two people marry, we say they're ______
  4. 5. if a flower is prettier than another, it's the ____