This special issue, focusing on different types of variation in syntactic complexity, offers a critical discussion of the role of variation in syntactic complexity research in SLA. Special attention is paid to inter‐learner variation (i.e., individual developmental trajectories of acquiring syntactic complexity) and to interactions with related constructs, for instance between syntax and morphology, and between syntactic and lexical complexity. The overarching focus of the different contributions is to investigate the possible variation of (syntactic) complexity according to various external factors, such as levels of linguistic proficiency (developmental variation), variation in task modality (i.e., oral, written), task types and genres, and variation in source and target languages (cross‐linguistic variation)

中文翻译：

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句法复杂性的变化：介绍

本期特刊关注句法复杂性中不同类型的变异，对变异在 SLA 中句法复杂性研究中的作用进行了批判性讨论。特别注意学习者间的差异（即获得句法复杂性的个体发展轨迹）以及与相关结构的相互作用，例如句法和词法之间以及句法和词汇复杂性之间的相互作用。不同贡献的首要重点是根据各种外部因素调查（句法）复杂性的可能变化，例如语言能力水平（发展变化）、任务模式的变化（即口头、书面）、任务类型和流派，以及源语言和目标语言的变化（跨语言变化）