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prior; beforehand; in advance; before the fact; ex ante
事前に予約しておかないと入れないお店だ。
It's a restaurant you can't get into without a prior reservation.
面接の事前準備をしっかりと行った。
I thoroughly made preparations in advance for the interview.
イベントの事前告知が十分に行われなかった。
Prior notice of the event was not adequately provided.