I have a co-worker who's always removing the word "that." I think that she's being excessive, and that a lot of the "that"s are needed. Who's right?
Well, it depends. Do you want your office's writing to be clunky, cumbersome and awkwardly formal? Then you're absolutely right. Or would you rather it sound like the English language?
It's been proven mathematically that 91 percent of all instances of the word "that" can be removed without affecting the meaning or comprehension of the sentence one whit. (Okay, it hasn't, but I do words, not math; 91 percent sounds about right.) "That" clutters up the sentence, and removing it is one of the easiest, cleanest ways to make your writing sound breezy and edited.
Take your question: "I think that she's being excessive" becomes "I think she's being excessive," and bam, you haven't wasted my time as a reader. Way to go.
The wimps at the Associated Press say to include the "that" when in doubt: "Omission can hurt," they say. "Inclusion never does." But they're neglecting the aesthetic hurt you're inflicting on my soul by writing an ugly, wordy sentence. Say goodbye to all "that"s that you don't need.
In the paper two weeks ago you had "octopi" as the plural of "octopus." But isn't that wrong, since "octopus" comes from Greek, not Latin?
"Octopi" isn't quite wrong, but it's not as right as most people think it is.
You're correct that "octopus" comes from Greek, so the preferred plural is actually "octopuses." (The Brits sometimes say "octopodes." Technically, that's hyper- correct, but as usual, when they say it, we have no idea what they're talking about.) But "octopi" is common enough that it's become almost as acceptable as "octopuses."
Unfortunately, there's no etymological argument for "octopi" over "octopodes." For the same reason Americans prefer pizza to spanikopita, mozzarella over feta, "octopus" got pulled from Greek over into Latin. It was probably annoying at first--like those people who now obnoxiously use words like "media" and "data" exclusively in the plural.
But now the Latin rules, even if it is erroneously, meaning more people say "octopi" than are willing to eat it.