A black swan event is an improbable and unforeseeable occurrence.

黑天鹅事件指不太可能发生和无法预见的事件。

A grey rhino event refers to an obvious but neglected threat.

灰犀牛事件指明显会发生而又被忽视的威胁。

We should stay alert to “black swan” and “gray rhino” events.

我们既要警惕“黑天鹅”事件，也要防范“灰犀牛”事件。

来源：同文世纪翻译，转载请注明出处！