字典解释

名词“occasion”有很多个意思，比如“场合” “时机” “特别时刻”等。它的形容词“occasional”意思比较单一，是“偶尔的”，常用、好用，值得掌握。它的副词“occasionally”（“偶尔地”）也可以顺便收入囊中。当我们想表达某个现象偶然才出现或某个事件偶然才发生时，除了使用 sometimes, from time to time, every now and then 之外，还可以使用 “occasional”和“occasionally”，尤其是在书面表达中。

例句

Johnny Chan is a formidable poker player and only loses very occasionally.

Although I am well travelled, I have mostly visited different parts of my own country. I have traveled abroad only occasionally.

这句话也可以表示为

Although I am well traveled, I have mostly visited different parts of my own country and have made only occasional overseas trips.

An occasional plane passes overhead, perhaps to La Guardia, perhaps to JFK.(La Guardia 和 JKF是纽约市的两大机场)

He occasionally regretted the shame he had brought on his family, but for his victims and their relatives he felt nothing.

翻译练习

露西擅长山水画，偶尔也会画画油画

Lucy is good at painting mountains, but she also would paint some oil paintings occasionally.
参考翻译：

Lucy is especially good at traditional Chinese landscape painting(山水画), but occasionally she does oils too.

或

Though an expert on traditional Chinese landscape painting, Lucy does occasional oil painting too.

场景：在描述数据图表时，特别是线图的时候，描述线图的趋势经常会用到occasional这个单词。