preposition at end of sentence
Whether the preposition may come last.
A preposition may end a sentence: the hall she waited in. Moving the preposition forward is also standard: the hall in which she waited. That order sometimes makes a sentence stiff. Choose the clearer version.
Examples
Use That is the desk she stood at.
Use That is the desk at which she stood.
Use Where are you from?
Avoid From where are you?