frustrating crossword (don't say i didn't warn you)

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Across
  1. 2. what is a fish?
  2. 3. how many eyes does the average person have?
  3. 5. what can be round and also has legs
  4. 8. most people have this but old people and babies often don't
Down
  1. 1. what should you do to avoid death specifically to do with hydration
  2. 4. what is it i ask you?
  3. 6. how fast is the speed of light?
  4. 7. word to ask for the location of something