critical [ˈkrɪtɪk(ə)l] adj. 批评的，批判的；极重要的，关键的；（局势）严重的；（病情）危急的；挑剔的；评论性的
例句 These findings may seem discouraging, but it was heartening for scientists to learn that the critical period for fluent language acquisition might be
longer than previously thought.【2018-5《时代周刊》】
这些结果或许看上去令人沮丧，但对科学家来说，得知流利语言习
得的关键期可能比之前认为的要长，是一件鼓舞人心的事。
