아닌지

In a sentence

• 그것이 사실이 아닌지 확인해야 합니다.

  We need to verify if that is not true.

  In this sentence, '아닌지' is used to express uncertainty about whether something might not be true.

• 이것이 우리가 찾던 것이 아닌지 고민해 봅시다.

  Let's think about whether this is not what we were looking for.

  Here, '아닌지' reflects a questioning or speculative stance on whether something does not meet the desired criteria.

• 그가 도와줄 사람 아닌지 궁금해요.

  I wonder if he is not the person to help.

  '아닌지' in this case conveys curiosity about whether the subject doesn't match certain characteristics