By Prefixes, Difference between

How To Learn English ? PART 2 Learning a language is mainly based upon self-struggle. Maybe the only thing to be done by the teachers on this subject is to advise a method. Because, in a sense, language cannot be taught but learned. So, it’s suitable that the students are shown ways to...

There is no rule. Words with these prefixes have come about through accidents of history. The most usual is "un-", but always consult a dictionary. The following does not really answer your question, but you may find it somewhat useful anyway, especially if you're willing to work to dig some...