What do the superheroes do?

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Across
  1. 2. The superheroes saves the:
  2. 3. Comes from the another planet
  3. 5. How the superheroes do this?
  4. 7. Comes from an island
  5. 8. Saves Gotham City
Down
  1. 1. Batman's worst enemy
  2. 3. What the superheroes do?
  3. 4. Who they save?
  4. 6. Where do they live?