关键时期假说是语言学习领域里的一个重要理论假设,对第二语言和外语教学具有重要的指导意义。该假设自60年代提出以来,一直是二语和外语教学研究中争论最激烈的话题之一。本文首先就80年代末以来对于关键时期假说的几种主要观点进行了综述,然后在研究比较这些观点的基础上认为,这些理论最终都直接或间接地证明了关键时期存在的合理性。 The key period hypothesis is an important theoretical hypothesis in the field of language learning and has important guiding significance for the second language and foreign language teaching. This hypothesis has been one of the most controversial topics in the field of second language and foreign language teaching research since its introduction in the 1960s. Based on a comparison of these views, the article first summarizes several key views on the key period hypothesis since the late 1980s and concludes that these theories ultimately and directly prove the rationality existing in the critical period.