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brisk and efficient; diligent; devoted; spirited
彼女は甲斐甲斐しく世話をした。
She took devoted care of him.
祖母は朝から晩まで甲斐甲斐しかった。
My grandmother was brisk and diligent from morning until night.
普段は甲斐甲斐しくない彼が、今日は率先して動いていた。
He's usually not diligent, but today he was taking the initiative.