Making a comparison with Who/Whom I now have a question about the use of what with prepositions in questions. I'll explain by example:
These two sentences are correct, one is more formal than the other:
- Formal: With whom are you doing that?
- Informal: Who are you doing that with?
But if I substitute Who/Whom with What, the "formal" one sounds a bit awkward and I'm not sure if it's correct or not:
- With what are you doing that?
- What are you doing that with?
So, are those last two questions grammatically correct?
Is one more formal than the other?