1. 碰巧碰上[发现]：happen in with 偶然和...碰见 | happen upon 碰巧碰上[发现] | happen on 碰巧碰上[发现]

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 uponchance uponcome acrosschance onattaindiscover