https://en.wikipedia.org/wiki/Polarity_item In Chinese, 哪 in a negative or interrogative environment changes its meaning to “any” 1. 没有哪件事比这更重要 - there isn’t any thing more important than this 2. 有没有哪一次是你印象特别深的 - is there any time that left a deep impact on you? (And explain which one) 没有 and 有没有 create the negative and interrogative environments, and 哪 is the polarity item Without 「哪」in the second example, the meaning changes 1. 有没有一次是你印象特别深的? - was there a time that left a deep impact on you (yes no, not requesting further detail)