Inventions that changed the world

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Across
  1. 2. was used to behead people during the French Revolution.
  2. 6. Helps peoplshopng in super markets
  3. 7. First antitank Weapon
Down
  1. 1. Played a minor role in jazz
  2. 3. The lightest known solid
  3. 4. Saves lives in a car crash
  4. 5. Autonomous machines