Mid Autumn Lantern Riddles

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Across
  1. 1. Which is faster? Hot or Cold?
  2. 4. What comes down but never goes up?
  3. 5. What has keys but can't open locks?
  4. 7. What can you break, even if you never pick it up or touch it?
Down
  1. 1. I am always in the past, never in the future, what am I?
  2. 2. What is always coming but never arrives?
  3. 3. What is so fragile that saying its name breaks it?
  4. 6. What has many teeth but can't bite?