overhear
/ˌəuvəˈhɪə(r); ˌovɚ`hɪr/ v
(pt, pp overheard /- 5h\\:d; -`h[d/) [Tn, Tng, Tni]
hear (sb, a conversation, etc) without the knowledge of the speaker(s); hear by chance 偷听到（某人说话、 谈话等）; 无意中听到
I overheard their argument/them. 我偷听到他们争论[他们说话].
I overheard them quarrelling. 我无意中听到他们吵架.
I overheard him say/saying he was going to France. 我偶然听到他说他要到法国去.