Many students have been coming to G.I.L and asking about prepositions at the end of sentences.
When you were at school you were probably taught that prepositions should not be at the end of a sentence.
Unfortunately there are situations where you have to use a preposition at the end, otherwise it would sound unnatural.
For example in some passive expressions:
So you can clearly see with these examples there is a need to put a preposition at the end.
Ending a sentence with a preposition is completely natural and acceptable in modern English.
If you would like more advice on this please come to G.I.L and feel free to ask your friendly teacher for more exercises on this!!!