Second language learning is a complex process that involves acquiring proficiency in a language other than one's native language.
第二语言学习是一个复杂的过程，涉及在母语之外的语言中获取熟练程度。
The study of second language learning helps educators develop effective teaching strategies.
对第二语言学习的研究帮助教育者制定有效的教学策略。