Abstract The present study examines adolescent and adult English-as-Foreign-Language (EFL) Learners’ linguistic complexity and register flexibility in writing across academic and colloquial contexts. A total of 263 EFL learners from three first language (L1) backgrounds (Chinese, French, and Spanish) participated in this study. Each participant produced two written texts on the same topic: a personal email to a close friend and an academic report to an educational authority. A total of 526 texts were analyzed for lexical, syntactic, and discourse organizational features. Multilevel modeling results revealed positive associations between participants’ English proficiency and their textual linguistic complexity. In contrast, the association between English proficiency and register flexibility was not consistent across the different linguistic levels analyzed and across the three L1 groups. Findings inform the design of pedagogical practices that anticipate the unique communicative challenges faced by EFL learners and teach communicative functions of complex linguistic forms.

中文翻译：

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超越语言复杂性：评估跨语境 EFL 写作的语域灵活性

摘要 本研究考察了青少年和成人英语作为外语 (EFL) 学习者的语言复杂性以及跨学术和口语环境写作的注册灵活性。共有来自三种第一语言 (L1) 背景（中文、法语和西班牙语）的 263 名 EFL 学习者参与了这项研究。每个参与者就同一主题制作了两份书面文本：一封给密友的私人电子邮件和一份给教育机构的学术报告。共分析了 526 篇文本的词汇、句法和话语组织特征。多层次建模结果揭示了参与者的英语熟练程度与其文本语言复杂性之间的正相关。相比之下，英语熟练程度和语域灵活性之间的关联在分析的不同语言水平和三个 L1 组中并不一致。研究结果为教学实践的设计提供了信息，这些实践预测了 EFL 学习者面临的独特交际挑战，并教授了复杂语言形式的交际功能。