Student or Learner
Be careful not to write the word of when you mean have or 've: I could've told you that not I could of told you that. The mistake arises from the fact that the pronunciation of have in unstressed contexts is the same as that of of, and the two words are confused when writing them down.
(From having - WordReference.com Dictionary of English)
Are there any words left out after "...are confused when"? Has "you are" been omitted?
...and the two words are confused when writing them down.
Could I ask if there are any words omitted between when and writing?