She came upon him unawares when he was searching her room.

他在翻她屋子时，冷不防被她撞见了。

《牛津词典》

This desire suddenly came upon Tom one day.

有一天，汤姆突然有了这个愿望。

youdao

Suddenly, she came upon a little three-legged table.

突然，她发现了一张三条腿的小桌子。

youdao

In fifteen thirty-five, a ship carrying the Roman Catholic Bishop of Panama came upon the Galapagos accidentally.

VOA: special.2009.12.16

In a battle between the Athenians and their neighbors near Eleusis he came to the assistance of his countrymen, routed the foe and died upon the field most gallantly.

在一场雅典人和其邻居,埃莱夫西斯的战争中,特勒斯在同胞的援助下击败了敌人,最后英勇地战死疆场

耶鲁公开课 - 古希腊历史简介课程节选

The reason for that I think is that the early times in which these civilizations arose saw all kinds of dangers coming, and the most--the swiftest, the least suspected, the one that could come upon you overnight came from the sea.

在我看来原因是,在这些文明所诞生的早期世界危机四伏,而来的最迅速,最难以预测,最可能,一夜之间骤然降临的灾难,正来自于海上

耶鲁公开课 - 古希腊历史简介课程节选

When we came upon a hamlet in such deep mountains, it seemed almost mysterious.

NPR: Literature and Lullabies from the 'Axis of Evil'

While there, we came upon another woman who was also in labor and carrying twins.

FORBES: Most Maternal Deaths Due to Preventable Health Risks

Watkins came upon the idea for Lapdap 20 years ago as a young researcher in Kenya.

FORBES: A Cure for Neglect