What is the difference between "at" "with", and "on" in the sentence.
Good luck AT class tonight.Good luck WITH your classes.Good luck ON your test tonight.I don't know the difference between these prepositions, please let me know that.

Thank you for the comment.&nbsp;

Good luck AT your class " probably I wouldn't use it, guess " I would use " in your class" because it would be making a reference to "classroom". Regarding to next cases "you may use both sound perfectly correct for me"