"모험하는 것은 때때로 위험합니다."
Translation:Going on an adventure is sometimes dangerous.
때 = time; instance 때때로 (adv) = at times; time and again
가끔 (might have chinese origin "각" for 'moment'. Not sure) = once in a while; on a few occasions (edging towards, "rarely")
The two expressions are used synonymously to mean 'sometimes'. The difference (I guess) is similar to that between 'many' and 'a few'.
"Adventuring is sometimes dangerous" was marked wrong here. Any reason why?