这类暴力事件在我们镇上是罕见的。

Such violent incidents are a rare ___occurrence in our town.

研究人员注意到这种疾病在沿海地区的发生率更高。

Researchers noted a higher ___occurrence of the illness in coastal regions.

这次罢工是一次打乱服务的意外事件。

The strike was an unexpected ___occurrence that disrupted services.