COMMON MISTAKES
There are two very common mistakes in apostrophe use, and both come from not following the rules set out above:
Its, It's and Its': The possessive form of the word "it" is "its", without an apostrophe anywhere, because it is a pronoun and follows the special rules for possessive pronouns. It's can only mean it is, or it has following the rules for contractions, and depending on context, and it's doesn't exist at all, since the plural of it is they.
plowned.