二语习得研究提出了附带词汇习得（或词汇偶然习得）假说，认为学习者在广泛的阅读过程中力图理解语言所传递的信息时不经意地习得了部分母语和外语词汇。它和有意学习或直接学习相辅相成。但是，单纯依靠泛读附带习得词汇几率低，数量少，因此，研究者们就探索各种干预手段来提高阅读中词汇附带习得的效率。这些干预手段中包括加注释及以生词为中心的任务。本研究旨在考察汉语、英语注释及以生词为中心的任务各自对词汇偶然习得及保持的影响。本文属于实证研究，包括一项阅读试验，两次词汇测试。本试验采取了完全随机、实验组、控制组和后测设计的实验方法，抽取了100名（有效受试数为99名）某重点中学高中二年级学生作为受试者。实验之前对他们进行了随机分组，他们近两次英语考试成绩的统计显示四组无显著性差异。这四组被随机分配到控制组（无注释组）及三个实验组中（汉语注释组，英语注释组及以生词为中心的任务组）。这四组分别阅读一篇无注释，汉语注释，英语注释及无注释有任务的文章。这四篇文章内容相同。两项测试分别为即时词汇测试及一周以后举行的延时词汇测试。本文通过对两项词汇测试收集了学生对目标词的掌握情况，然后使用了SPSS 13.0 对原始数据进行了处理和分析。包括描述统计分析，单因素方差分析(one-way ANOVA),事后检验 (Post Hoc Scheffe test) 及独立样本T 检验(Independent Samples Test)。研究结果表明：1) 注释对词汇偶然习得及保持都要比无注释要好，而且有显著性差异；2) 汉语注释及英语注释对词汇偶然习得没有显著性差异。但是，外语注释在一周后对习得的保持要更好；3)以生词为中心的任务组对词汇偶然习得及保持要比控制组好，并且有显著性差异；4）汉语注释，英语注释及以生词为中心的任务都被证实是提高学生在泛读中偶然习得词汇效率的有效干预手段，但三者之间没有显著性差异。本研究具有理论和实践意义，对英语泛读教材和课外读物的编写及英语教学有积极的指导作用。对教材编写者及教师来说，在外语注释能被理解的前提下要多使用外语注释，这样有助于学生的英语思维。并且，尽管以生词为中心的任务有助于为学生推测出生词词义提供线索，但是在给学生增加这种任务时是要慎重， 因为学生也有可能选择错误词义。

It is a widely held view that much of second language is acquired incidentally during extensive reading for meaning. However, it is slow and incremental. Consequently, researchers begin to explore instructional interventions including input modifications by way of glossing and word-focused tasks to promote incidental vocabulary acquisition. The present study attempts to investigate the respective effectiveness of L1 and L2 glosses and a word-focused task of multiple-choice comprehension questions on incidental vocabulary acquisition and retention.The completely randomized controlled post evaluation with control group design was conducted to achieve the objectives. The subjects were 100 (valid subjects were 99) Chinese second-year students from a key senior school. They were randomly divided into four groups. Each group were randomly assigned to one of the four reading conditions: original passage with no glosses, modified passage with L1 glosses, modified passage with L2 glosses and modified passage with a word-focused task. After reading, they were immediately given an unexpected vocabulary test to assess the acquisition of the 12 target words. One week later, a delayed test identical to the immediate test were given to the subjects without any forewarning. The results indicates that 1) reading with glosses led to better incidental vocabulary acquisition and retention than reading with no glosses; 2) both reading with L1 and L2 glosses yielded almost equal incidental vocabulary acquisition and retention, and reading with L2 glosses showed less word loss over the course of one week; 3) reading with a word-focused task showed superior word knowledge gain over reading with no cues (the Control group); and 4) L1 glosses, L2 glosses and the word-focused task were proved to be effective on improving incidental vocabulary acquisition and retention, yet there were no statistical significance between these three instructional interventions. The present study takes a step to explore the effectiveness of instructional interventions on incidental vocabulary acquisition in printed extensive reading texts and sheds light on the design of reading texts and on future research in this field.