We are the casual acquaintance of a long railway journey.

我们是在火车长途旅行中偶然结识的朋友。

She was a casual acquaintance in Vienna.

她是我在越南的一个熟人。

He described himself as a casual acquaintance of the Kennedys'.

他称自己是肯尼迪夫妇的泛泛之交。

To the casual acquaintance, you may appear dangerously pretentious.

和不太熟悉的人在一起时，这样做或许有炫耀之嫌。

Their casual acquaintance developed over time into a lasting friendship.

他们偶尔中相遇，但随着时间的流逝，却产生了永久的友谊。