六月下雪在这里是极其罕见的事情。

Snow in June is an extremely rare ___occurrence here.

暴风雨期间，停电是常有的事。

Power outages were a frequent ___occurrence during the storm.

他的突然离开是个出人意料的事件，让所有人都感到困惑。

His sudden departure was an unexpected ___occurrence that left everyone puzzled.