occur的名词形式是occurrence
occurrencen.发生的事情;存在的事物;发生;出现;存在
occurv.发生;出现;存在于;出现在
Complaints seemed to be an everyday occurrence
似乎每天都有投诉。
Extreme weather is a rare occurrence in that country.
那个国家不常出现极端天气。
Traffic jams are a common occurrence in that area.
那一地区常常堵车。
