st- and -st words

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Across
  1. 4. to take a break
  2. 7. opposite of go
  3. 9. you might put this on an envelope
  4. 11. a bird's home
  5. 12. to get up from sitting
  6. 13. not found
Down
  1. 1. 4 + 5
  2. 2. the price of something
  3. 3. to give aid to
  4. 5. opposite of finish
  5. 6. when you move forward you take one of these
  6. 8. good better _______
  7. 9. a small piece of rock
  8. 10. a necessity
  9. 12. part of a plant