When Can a Sentence End with a Preposition?
Here's an example of a sentence that can end with a preposition: What did you step on? A key point is that the sentence doesn't work if you leave off the preposition. You can't say, “What did you step?” You need to say, “What did you step on?” to make a grammatical sentence.
I can hear some of you gnashing your teeth right now, while you think, “What about saying, 'On what did you step?'” But really, have you ever heard anyone talk that way? I've read long, contorted arguments from noted grammarians about why it's OK to end sentences with prepositions when the preposition isn't extraneous (1), but the driving point still seems to be, “Nobody in their right mind talks this way.” Yes, you could say, “On what did you step?” but not even grammarians think you should. It sounds pedantic.
I've read long arguments about why it's OK to end sentences with prepositions when the preposition isn't extraneous, but the driving point still seems to be “Normal people don't talk that way.”
didn't even cross my mind...
Berkeman and I are fighting a losing battle to stop slang. A guy I dated once told me that my use of proper English when speaking made me sound Shakespearean, and he didn't mean it as a compliment. 
Yes, much better.
