to be caught off guard by something意外遭遇

英文释义

To be unprepared for something.

例句

Since the day had started without a cloud in the sky, we were caught off guard by the afternoon rainstorm that ruined our picnic in the park.

今天一早天空中还没一丝云彩，下午却下起了暴雨，破坏了我们在公园的野餐。