How do we measure time?

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Across
  1. 1. Twelve months make this.
  2. 3. To turn around quickly.
  3. 5. Sixty seconds make this.
  4. 9. The path of a planet around the Sun.
  5. 10. One hundred years.
  6. 11. An area with the same time.
  7. 13. Ten years.
  8. 15. Twelve o'clock at night.
  9. 16. Sixty minutes make this.
Down
  1. 2. An invisible line that Earth spins on.
  2. 3. The shortest unit of time.
  3. 4. Two weeks.
  4. 6. Twelve o'clock in the middle of the day.
  5. 7. Seven days make this.
  6. 8. To add a number to itself a few times.
  7. 12. About 30 days make this.
  8. 14. Twenty-four hours make this.