occasional
adj. /əˈkeɪʒənl/ B1
偶尔的；偶然的
Happening sometimes, but not regularly or often.
仙境例句
Apart from an occasional snore, the Dormouse said nothing all afternoon.
除了偶尔打几声呼噜，睡鼠一下午什么也没说。
原著这一句
These words were followed by a very long silence, broken only by an occasional exclamation of “Hjckrrh!” from the Gryphon, and the constant heavy sobbing of the Mock Turtle.
这番话后是一阵长长的沉默，其间只有鹰头狮偶尔发出一声“赫克咯！”的怪叫，以及假海龟持续不断的沉重抽泣打破了寂静。
卡罗尔原著 · 第 9 章