My two cents on using “they” as a singular pronoun: it’s acceptable in spoken English, but not in written English. In writing, one should use “he or she” unless one has to repeat it more than once in succession, or if one has to use the reflexive form, at which point it just gets too awkward. In that case, one should just use “he” or “she.” And for crying out loud, don’t ever write “he/she” or “(s)he.” Shudder.

I also note that Tim Sandefur shares my biggest grammatical peeve: signs at the checkout aisle that say “10 items or less.” It’s “10 items or fewer.” Use “less” with mass nouns (“Less than 10 inches of snow”) and “fewer” with count nouns (“Fewer than 10 cats”).

It’s interesting that “more” works with both mass nouns and count nouns.