Has the language really changed this much in twenty years? "None of your students have showed up" - a sentence supplied by this very website as a proper one - seems wrong on two counts to me.
Twenty years ago (or in my high school and college) "none" took a singular verb, as did "no one" and "nobody" and "nothing." And the past perfect of "show" was "shown." Show, showed, shown. They will show up. They showed up yesterday. They had already shown up.
In this example sentence ("None of your students have showed up...") I cringed two times. Shouldn't it read, "None of your students has shown up..."?
Or am I really that old?