偶一為之

to do sth once in a while (idiom) / to do sth more as an exception than the rule

accidental / image / pair / mate

accidentally / once in a while / very occasionally

one / single / a (article) / as soon as / entire; whole; all; throughout / "one" radical in Chinese characters (Kangxi radical 1) / also pr. [yao1] for greater clarity when spelling out numbers digit by digit

as (in the capacity of) / to take sth as / to act as / to serve as / to behave as / to become / to be / to do / by (in the passive voice)

because of / for / to

(possessive particle, literary equivalent of 的[de5]) / him / her / it