Crossword Puzzle

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Across
  1. 4. Happening from time to time
  2. 5. Twilight, nightfall
  3. 8. Active at night
  4. 9. Active in the day
Down
  1. 1. Happening before the proper time
  2. 2. A span of a thousand years
  3. 3. Happening every hundred years
  4. 6. Noteworthy period of time
  5. 7. Lasting a short time