The uninflected verb "to dance" is 춤추다, yet Duolingo has informed me that if I wish t say that "subject dances" (with a deferential ending) then the sentence will be "subject 춤을 춥니다"
Why is this sentence to 춤을 춥니다 (addition of the direct object particle) rather than "subject 춤춥니다" ?
What is the general concept at play here?