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half century
二人は半世紀にわたる友情を育んだ。
The two of them nurtured a friendship spanning half a century.
その建物はすでに半世紀以上の歴史を持つ。
That building already has a history of more than half a century.
半世紀前の記録が今になって初めて公開された。
Records from half a century ago have now been made public for the first time.