I don't know anything about English syntax, but Mark's reference to Churchill's example of the avoidance of preposition-stranding reminded me of my favorite example of preposition-stranding. I don't know who came up with it. The context is that a little girl and her father have discussed what her bedtime story will be, but when he goes up to her room, he brings the wrong book. She says:
Daddy, what did you bring that book that I didn't want to be read to out of up for?It is possible to remove the stranding of the propositions, but only by a significant rearrangement, including a change from passive to active and the use of why instead of what ... for. The result is quite stilted:
Daddy, why did you bring up that book out of which I didn't want you to read to me?There doesn't appear to be any way to avoid preposition-stranding if you use what ... for rather than why. Substituting what for for why is ungrammatical:
*Daddy, what for did you bring up that book out of which I didn't want you to read to me?Moving for to the end makes the sentence acceptable:
Daddy, what did you bring up that book out of which I didn't want you to read to me for?So it appears that the what ... for construction requires preposition-stranding. Interestingly, in my opinion, although the last version is acceptable, it is still rather awkward. By far the most natural of these sentences is the first, with the long string of stranded prepositions.