Ответ:

  1. off — If you set off at 7 o'clock, you should get here by 11:00. (отправиться)
  2. across — I ran across some old photographs. (случайно обнаружить)
  3. up — to set up a new business. (открыть, организовать)
  4. for — What does ATM stand for? (расшифровываться)
  5. out — we had run out of money. (закончиться)
  6. in — I offered to stand in for Amy. (заменить)