〜することもある (translations)→ often sometimes
いつの間にか (translations)→ absentmindedly eventually naturally quickly suddenly
たまに (translations)→ few intermittently little occasional
ときおり (translations)→ periodically
ときどき (translations)→ part-time periodic several
何度か (translations)→ series some
思いだしたように (translations)→ erratic odd thoughtfully
