riddle me this puzzle no spaces

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Across
  1. 3. the more there is, the less you see, what could I be
  2. 4. how many sides does a cylinder have
  3. 7. what is at the beginning of eternity, after time and space, and at the end of every race
  4. 8. what has trees, and leaves, but no bark
  5. 10. what do you need to divide 16 apples among 17 people
  6. 11. what room can no one enter
  7. 13. if you give me food, I will live. if you give me water, I will die, What am I
  8. 14. how much dirt is in a hole 16 feet across, and 18 feet deep
  9. 15. If you throw me off a building, I will not break, but if you put me in the ocean I will
  10. 17. What has neither flesh, bone, nor nail yet has 4 fingers and a thumb
  11. 18. What is it that travels on all fours in the morning, on two legs at noon, and three at twilight
  12. 19. the more you take away, the more it grows, what am I
  13. 20. whats the single answer on your face
Down
  1. 1. what weighs six ounces, sits in a tree, and is very dangerous(Think of The Movie Batman [1966])
  2. 2. hit me hard, I will crack, but this wont stop me from staring back
  3. 5. What gets wetter, and wetter the more it dries
  4. 6. some of these questions are -------
  5. 9. If you know me, you'll want to share me but if you share me, I'll be gone. What am I
  6. 12. I am lighter than a feather, but yet the strongest man could not hold me for much more than a few minuets. what am I
  7. 16. what belongs to you but is used by others
  8. 21. 'what goes up white, but comes down yellow and white?'(think 1969)