1. only to find 結果卻發現 
  2. only/but/all too pleased/happy/thankful to do 做……太高興/感謝了 
  3. operate on sb. 給某人做手術 
  4. operation on sp. 在某位置動手術 
  5. opposite direction 相反方向 
  6. or rather 或者說、更進一步說 
  7. order (that) sb. (should) do 命令某人應該做某事(虛擬語氣) 
  8. ought not to have done 不應該做(卻做了) 
  9. ought to have done 應該做(卻沒做) 
  10. out of breath 上氣不接下氣
  11. out of one's reach 夠不著 
  12. out of order 壞了、無秩序、亂放 
  13. out of the reach of sb. 某人夠不到 
  14. over and over again 一次又一次、再三 
  15. over the radio 從收音機裡 
  16. over the years 這幾年裡 
  17. owe one's success to sb. 把某人的成功歸功於別人 
  18. owe one's thanks to sb. 感謝某人 
  19. owe sb. sth. 欠某人某物 
  20. owe sth. to sb. 把……歸於……