What was the question for this implicit rationale, and corresponding answer?
The little boy might be alone so the plural children cannot be inferred. Green swings can be found other places than just at a park.
 The answer: it is not possible to tell

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
The question: Given the sentence "A little boy sitting on a green swing." is it true that "Children at the park."?