Future travel

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Across
  1. 3. This is like a skateboard, but it doesn’t have wheels.
  2. 4. This is one of the fastest planes in the world.
  3. 5. This goes much higher than a plane.
  4. 6. When you put this on your back, you can fly in the air.
Down
  1. 1. This is very long, and it travels quickly from city to city.
  2. 2. This is also long, but it usually travels inside a city.