Last week we dealt with some possessive questions when there were plural possessors. Now we'll deal with other possessives, which are more complex than they appear, and plural possessives. Because we're trying to keep it simple, we'll ignore that this part of speech is really the genitive case, indicating more than just possession, but we'll stick with the basics, which always bear repeating.

Many of us learned that possessives are formed by adding "'s" to the possessor. That's fine for simple possessives, like "Romney's platform" or "Obama's policies." But if the possessor already ends in an "s," do you add just an apostrophe, or the apostrophe and another "s"? Well, that depends: on the stylebook you follow; on whether the word is a plural, singular, or proper noun; and on whether the moon is waxing or waning. (OK, maybe not that last one.)

For example, "the Republican's platform" is a singular possessive and refers to the platform of one lone Republican. "The Republicans' platform" represents the whole group. That's a plural possessive. Easy.

If the word is not a proper noun and ends in "s" in its singular form, some style guides call for just an apostrophe: "the boss' say-so." The Associated Press Stylebook, which many news organizations follow, calls for "boss's," unless it's followed by a word beginning in "s," so it would still be "the boss' say-so," but "the boss's order." But if the word is a proper noun ending in "s," add just an apostrophe: "Texas' delegates." (We warned you it was complicated!)

The New York Times Manual of Style and Usage tries to make it less complicated, calling for "'s" whether the word ending in "s" is a common or proper noun. However, it throws pronunciation into the mix: If the word ends in two "sibilant" sounds (the "s" and "s" in "Kansas," or the "x" and "s" in "taxes," for example), The Times drops the "s" after the apostrophe, so "Texas'" still rules. But (isn't there always an exception?) if that last "s" sound is silent, The Times says, keep the "s" after the apostrophe: "Arkansas's delegates."

Now, let's move on to plurals. As we saw with "Republicans'," most plurals get just the apostrophe, since they're already bringing an "s" to the party. That includes plurals formed with "es," as in "the bosses' say-so." But if the plural of the word is not formed with an "s," it gets the "'s" treatment, as in "the women's vote." If the plural form is the same as the singular, and does not end in "s," it also gets the full treatment: "the deer's tracks," though the context needs to tell the reader whether the tracks were made by one deer or more. And if the singular form is really referring to a plural concept, like "politics," treat it like a plural and make it "the politics' cycle." That goes for our great nation, too: "The United States' election cycle" is the one to use. Luckily, nearly every style guide agrees on those.

It's a quirk of English that all of our personal possessive pronouns are absent apostrophes: "yours," "mine," "ours." That includes — ahem — "its," no matter how many times you're tempted to use "it's policies." That's an apostrophe too far.