He treated them seriously and, on occasion, entertained them hilariously.他对他们很严肃, 但有时候也会逗得他们哈哈大笑。

He translated not only from the French but also, on occasion, from the Polish.他不仅做法语翻译, 有时也做些波兰语翻译。

Some of the players may, on occasion, break the rules.一些运动员有时候可能会违反规则。