我无意中听到他在告诉她他要离开了。

I ___overheard him telling her he was leaving.

我曾无意中听到一个刚从意大利回来的人说了一句话。

I once ___overheard a remark from a person who had just been in Italy.

她声称无意中在咖啡馆听到竞争对手在讨论他们的策略。

She claimed to have ___overheard the competitors discussing their strategy at the cafe.