A common English grammar rule says that sentences cannot end with a preposition. This rule was derived from languages like Latin and French, in which it is grammatically impossible to put a preposition at the end of a sentence. Unfortunately, the rule is easy to break in English, and nowhere is this more evident than with phrasal verbs. The 'rule' that you shouldn't end a sentence with a preposition is considered a myth by some, and dates back to the 18th Century, when some Grammarians.
Technically speaking, it is not always incorrect to end a sentence with a, although, in most cases, sentences can be rewritten to avoid a preposition at the end. The only time you absolutely should not put a preposition at the end a sentence is when there is no direct object.Upon first glance, it may seem that some words at the end of a sentence are prepositions, when in fact they are parts of the. For example, a sentence ending with 'put up' or 'put up with' is not grammatically incorrect. In these cases, 'up' and 'up with' are adverbial particles.In general, it is acceptable to end a sentence with a preposition to avoid confusion or as part of casual conversation and writing. For example, it is acceptable to write or say “Where are you from?” While it could be reworded, it would be awkward and extremely formal to say “From where are you?”It’s a common myth that the English language contains a rule banning prepositions at the end of a sentence, although Latin does have such a rule. In a few cases, it is undesirable to end a sentence with a preposition. In the case of a very long sentence, the ending preposition could be quite a distance from its object, making the sentence confusing.
When I was growing up, my English teachers always marked off for ending a sentence with a preposition. If we answered a question in class and ended our sentence with a preposition, they would also reprimand us and make us reword our answer correctly. The command 'do not end a sentence with a preposition' was drilled into us for years.My grandson asked me to proofread an English term paper and I noticed he ended quite a few sentences with prepositions. There were a lot of sentences like 'I don't know who he hangs with.'
And 'Where's he going to?' I said something about not ending sentences that way, and he said his teacher doesn't really enforce any rules about prepositions. She thinks it's better to be clear than to be too formal. I have to say I agree, but it's a hard habit to break after all these years.