Lol so glad this topic was created! I don't like "whilst" instead of "while." It sounds pretentious while in most cases it's not meant to sound that way. This is an obvious one but it also drives me crazy how the word hospital is used e.g. "he's gone to hospital." No, he's gone to THE hospital. You wouldn't say "he's gone to restaurant" or "he's gone to bank"!
But you do say "He's gone to school", "He's gone to college" and "He's gone to work"... it's the same principle (it's talking about the purpose of the building vs. the building itself).
If you are a patient, you "go to hospital" (you are admitted to hospital for treatment), but if you are visiting someone, you go
the hospital (you are not a patient, you are visiting someone who has been hospitalised).
Your child "goes to school" (they are a pupil), but you go to
the school to pick them up.
You "go to college" (you are a student), but your parents go to
the college to visit you.
It's just an odd quirk of the English language that's used in the UK, but not in the US

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