Batman and the ultimate riddle

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Across
  1. 1. someone who commits a crime
  2. 3. a sound that is heard after it has reflected off a surface such as a wall
  3. 7. reach a place at the end of a journey
  4. 8. something that is confusing or a problem that is difficult to solve
  5. 9. to destroy something such as a building
Down
  1. 1. take someone as a prisoner
  2. 2. a very tall modern building
  3. 4. quick to understand and learn ideas
  4. 5. Batman's sidekick
  5. 6. top of a room