Three possible scenarios:
1. Who's = Pronoun + verb
2. Who's = Possessive proper noun
3. Whose = Pronominal adjective
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1. If the sentence makes sense by substituting "Who is", then "Who's" is correct.
2. If you can substitute "of Who" after the following noun, then "Who's" is correct.
3. If you can substitute "of whom" after the following noun, then "Whose" is correct.
Examples:
1. Who's here?
Who is here? "Who's" is correct.
"Here" is not a noun, so "whose" is impossible.
2. This is Who's house. "Who" is a proper name.
This is Who is house. "Who's" looks incorrect.
This is the house of Who. "Who's" is correct.
3. This is whose house? "Who" is not a proper name.
This is who is house? "who's" is obviously wrong.
This is the house of whom? "whose" is correct.
mmerlinn
"We've found by experience that people who are careless and sloppy writers are usually also careless and sloppy at thinking and coding. Answering questions for careless and sloppy thinkers is not rewarding." - Eric Raymond
Poor people do not hire employees. If you soak the rich, who are you going to work for?