Definition
Used to describe something that happens or is done continuously every day, often something monotonous or tedious.
日复一日（尤指枯燥之事）
She works a repetitive job at the factory day in day out.
她在工厂里日复一日地做着重复的工作。
He practices the piano day in day out, hoping to become a musician.
他日复一日地练习钢琴，希望能成为一名音乐家。
I'm tired of eating the same food day in day out.
我厌倦了日复一日地吃同样的食物。