Student or Learner
Is there any rule when to use preposition before or after?
e.g. For who? Who for?....In which bag is it? Which bag is it in?
Thank you very much!
"It is for you". "It is in this bag".
As you know, word order changes with questions. All of your examples are questions, so you might only be having trouble there.
"For whom is it? Who is it for?" mean the same. (The latter is more common).
Your two sentences about the bag are both correct.
Prepositions often come at the end of a question.
What did you do that for? = *For what did you do that = Why did you do that?
Since the questions you've posted are all correct, why not try some harder questions with prepositions that you're not sure of, and we'll see if you've got it right?