Riddles

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Across
  1. 3. What building has the most stories?
  2. 4. What beings with an "e" and only contains one letter?
  3. 5. Throw away the outside and cook the inside, then eat the outside and throw away the inside. What is it?
Down
  1. 1. What can travel all around the world without leaving its corner?
  2. 2. What is so fragile that saying its name breaks it?