One day he just upped and left.

有一天他突然离开了。

《柯林斯英汉双解大词典》

One day he left, disappeared without a trace.

有一天他离开了，消失得无影无踪。

《柯林斯英汉双解大词典》

My prayer is that one day he will walk again.

我的企盼就是有一天他能重新走路。

《牛津词典》

As he tells it,one day he looked in the window of a school and noticed how dark it was.

VOA: special.2009.12.21

I just basically do year-one to the present, it's was nice warm outside, that was the day he was born.

我到现在做了一年，那天户外很晴朗暖和，那天他出生了。

麻省理工公开课 - 媒体、教育、市场课程节选

Winston Churchill never, never conceded that it was Istanbul; he called it Constantinople till the day he died.

温斯顿·丘吉尔从没承认那里是伊斯坦布尔,直到死前他还叫那个地方君士坦丁堡

耶鲁公开课 - 古希腊历史简介课程节选

Every day he looks out his office windows and sees the ghosts of wrecked firms.

FORBES: Magazine Article

Every entrepreneur believes that one day he or she will be able to make this statement.

FORBES: Magazine Article

Kadian had been out on a bike ride with his family on the day he died.

BBC: Kadian Harding