nearly but not quite right...

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Across
  1. 2. nineteen fifty-nine
  2. 4. I can't UNDERSTOOD what you are saying
  3. 6. you need to use sharp scissors CAREFUL
  4. 10. The ice is very SLIP in the morning
  5. 12. I THINKED I saw a rabbit
  6. 13. I am going to do my homework FAST
  7. 14. I DONE it yesterday
  8. 15. In the middle of one and five
  9. 17. I can understand English GOOD
  10. 18. I haven't been out SINCE three weeks
Down
  1. 1. I haven't seen any snow AFTER last winter
  2. 3. this crossword is PUZZLE
  3. 5. miam! that pasta was TASTE
  4. 7. there isn't NOTHING in the bag!
  5. 8. I LEAVED home really early today
  6. 9. Let's cut the cake into THREES
  7. 11. You need to be QUIETLY in class at school
  8. 16. Let's cut the other cake in DOUBLE