1. 偶然遇见：chance to 偶然发生 | chance upon 偶然遇见 | chance 机会

2. 偶然遇见, 不期而遇：chance of a lifetime 千载难逢的良机, 一生中唯一的机会 | chance on 偶然遇见, 不期而遇 | chance upon 偶然遇见, 不期而遇

verb

1. find unexpectedly

e.g. the archeologists chanced upon an old tomb
she struck a goldmine
The hikers finally struck the main path to the lake

Synonym: fall uponstrikecome uponlight uponcome acrosschance onhappen uponattaindiscover