So again, they both know that someone in the room has a pink hat on their head: it is mutual knowledge that there's a pink hat in the room.

但是他们都知道,至少有一个人戴着粉色帽子,至少有一顶粉色帽子是相互知识

耶鲁公开课 - 博弈论课程节选

I saw an old lady wearing a big classical hat today.

今天我看到一个年迈的女人戴着一顶很大的复古帽子。

英国皇家赛马会 - SpeakingMax英语口语达人

He'd gone to Kentucky and drunk lots of Bourbon once, he carried an umbrella, that sort of middle class symbol of protection, and he is chased from the throne in 1848.

他去过肯塔基州,嗜好波旁威士忌,他有一顶保护伞,即他是中产阶级的象征,他在1848年被王室追捕

耶鲁公开课 - 1871年后的法国课程节选

I think I'm going to buy one, maybe next week.

我打算去买下那一顶，也许下周就去。

I like实战 - SpeakingMax英语口语达人