Prefixes (sub, uni, bi, tri, quad)

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Across
  1. 3. below the required standard
  2. 4. mythical animal with one horn
  3. 5. eyeglasses with two lenses
  4. 6. shape with three sides
  5. 7. to sink below the surface
  6. 8. to be increased by four
  7. 9. three colors
Down
  1. 1. shape with four sides
  2. 2. cycle with one wheel
  3. 5. twice a week