The Editing Ninja: Whose versus Who's

The apostrophe causes problems with these two homophones.  Whose is apossessive pronoun.
Incorrect: Who'scar is this?
Correct: Whosecar is this?
Who's is thecontraction of who and is. Again, the apostrophe (like withit's) indicates the omission of a letter.
Incorrect: Whoseon first using who's glove?
Correct: Who's onfirst using whose glove?
Simple, right?  And now you can steal from the Editing Ninja's arsenal in one handy digital package:

(Isn't he cute?)