Greek language: Ancient Greek did not have separate formal and informal second person singular pronouns. Modern Greek does. This is the only language I can think of that has gained a T-V distinction - though apparently it's losing it again. Make up your mind, Greek!
"..."! (削除) US vs. UK (削除ここまで) This user uses "logical quotation marks". Forcing internal punctuation leads to factual errors. It's not a nationalistic style issue!
; This user's favorite punctuation is semicolons; they like using them a lot.
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