Researchers also believe that, as in the first language (L1) acquisition, there is also a critical period (stretching roughly from 18 months to puberty) in SLA.

• 研究者们还普遍认为，像第一语言习得一样，第二语言习得也存在关键期（大约是从1岁半到15岁），关键期后开始学习第二语言很难取得好的成果。