模糊限制语的使用是语用能力的一个重要组成部分，在学术写作中具有重要作用。然而，以往研究较少关注研究生学位论文中模糊限制语的使用，也很少有研究提出模糊限制语语用能力成分的理论框架。有鉴于此，本研究尝试对研究生模糊限制语语用能力进行研究。在前人研究的基础上，本研究对比分析中国英语专业研究生学位论文和英语本族语研究生学位论文中模糊限制语的分布和使用，从语法知识、语类知识和作者身份三个方面探讨中国英语专业研究生的语用能力。
采用对比语言学方法，借助语料库工具，基于模糊限制语词表，通过AntConc（3.4.4版）软件对中国英语专业研究生和英语本族语研究生撰写的共58篇硕士论文中的模糊限制语进行检索和分析。通过分析两组硕士论文中模糊限制语的使用，本研究发现：
（1）与英语本族语硕士研究生相比，中国英语专业硕士研究生总体上使用的模糊限制语较少。在这两组论文中，中国英语专业硕士研究生使用情态助动词、副词、动词和形容词的频率显著低于英语本族语硕士研究生。这两组数据中名词出现的频率相似。结果表明，两组硕士研究生在模糊限制语的词汇语法选择偏好上存在差异性。中国英语专业硕士研究生过多依赖有限的模糊限制语表达认知情态意义，模糊限制语资源在完备性与多样性上还存在不足。
（2）与英语本族语硕士研究生相比，中国英语专业硕士研究生在摘要、引言、方法和结果/讨论/结论中显著少用模糊限制语。在摘要、引言、方法、结果/讨论/结论中，中国硕士研究生显著少用情态助动词和动词，在方法和结果/讨论/结论部分，副词和形容词的频率显著低。副词和形容词在两组硕士论文的摘要和引言中的频率相似，名词在中英硕士论文的摘要、引言、方法、结果/讨论/结论中的频率相似。模糊限制语策略选择的相似性表明，两组作者都意识到模糊限制语在调节语气强度和确定性方面的作用。两组硕士论文中模糊限制语频率和类型的差异表明，两组硕士研究生对语类知识和模糊限制语的功能有着不同的理解，在回应修辞情境时有不同的偏好。中国英语专业硕士研究生在学位论文中表达观点和实现语类交际目的时，承诺性和确定性程度高，试探性立场不显著。英语硕士研究生学位论文试探性程度高，对话性强。
（3）人称模糊限制语在中国英语专业硕士论文和英语本族语硕士论文中的频率存在显著差异。中国英语专业硕士研究生作者显著少用人称模糊限制语。尽管这两组学生都是学位论文的唯一作者，但中国英语专业硕士研究生在使用人称模糊限制语时倾向使用第一人称复数代词，避免使用第一人称单数代词。英语本族语硕士研究生在使用人称模糊限制语时，第一人称复数代词和第一人称单数代词的频率相近。研究结果表明，在建构作者身份时，中国英语专业硕士研究生更倾向于隐藏作者个人身份，凸显集体身份，将自身置于学科领域之内以获得认可。而英语本族语硕士研究生个体身份建构意识强，同时表现出与学术语篇共同体之间的联系，建构集体身份，拉近与读者的距离以获得认可。
本研究提出了模糊限制语语用能力成分框架，拓展了语用能力的理论探索，并对英语专业研究生在书面学术话语中的模糊限制语语用能力进行了探索性实证分析，这对二语语用能力和学术写作的研究和教学实践具有启发意义。

Hedging is one important aspect of pragmatic competence. It plays an important role in academic writing. However, few studies have examined master’s students’ (MA students) pragmatic competence in hedging based on analyses of adequate corpora of written academic discourse, and few studies on the pragmatic competence have proposed the framework of pragmatic competence in hedging. Thus, it is very necessary to conduct such a study on MA students’ pragmatic competence in hedging. Based on the previous studies, this study attempts to explore the frequency of hedges to investigate the Chinese English-major MA students’ pragmatic competence in hedging from three aspects: grammatical knowledge, genre knowledge and authorial identity. 
The contrastive linguistics approach is adopted to contrast and compare the use of hedges between the two corpora of 58 MA theses that were written by the Chinese English-major MA students and the English L1 MA students with the help of corpus linguistic method. The whole corpus was searched and analyzed via AntConc (Version 3.4.4) based on the list of hedges. By way of comparing the use of hedges in the two groups of MA theses, the key findings are as follows:
(1)The Chinese English-major MA students employed much fewer hedging devices overall. With regard to the lexicogrammatical choices of hedges, the Chinese English-major MA students used fewer modal auxiliaries, adverbs, lexical verbs and adjectives than the English L1 MA students. Similarity is found in the frequency of nouns in the two groups of data. Findings indicated that the Chinese English-major MA students had a more restricted range of hedging devices than the English L1 MA students. And they had different preferences for lexicogrammatical realizations of hedges from the English L1 MA students.
(2) In contrast with the English L1 MA student writers, the Chinese English-major MA student writers tended to use much fewer hedges in Abstract, Introduction, Method and Results/Discussion/Conclusion part-genres. They were inclined to use modal auxiliaries and verbs less frequently in Abstract, Introduction, Method and Results/Discussion/Conclusion, and used much fewer adverbs and adjectives in Method and Results/Discussion/Conclusion sections. Similar frequency was detected in the use of adverbs and adjectives in Abstracts and Introductions, nouns in Abstract, Introduction, Method and Results/Discussion/Conclusion in the two corpora. The similarities in the choices of hedging strategies indicated that both groups of writers were aware of the functions of hedges in modifying and mitigating the force and certainty of statements. By looking at the hedging devices contributing to the interactive side of academic writing, the differences in frequency and types of hedges in the two sets of part-genres in MA theses suggested that the Chinese English-major MA students and English L1 MA students might develop different preferences in responding to rhetorical situations. The Chinese English-major MA students were prone to displaying a higher level of assertiveness and commitment by using fewer hedges whereas the English L1 MA students preferred to promote a higher level of deference and open the space for negotiation with the readers when presenting claims and achieving the intentions of MA theses and its part-genres.
(3) In contrast with the English L1 MA students, the Chinese English-major MA students opted to be less visible in their texts by employing fewer personally attributed hedges. They were more likely to project their collective identity to gain recognition by preferring first person plural pronouns over first person singular pronouns when hedging. The English L1 MA students tended to project both their individual and collective identities by making a balance of the use of first person plural pronouns and first person singular pronouns when hedging both to present their claim as an individual interpretation, and to diffuse responsibility for a claim by making it seem collective. 
This study expands the theoretical exploration of pragmatic competence by proposing the construct of pragmatic competence in hedging and conducts an exploratory empirical analysis of the pragmatic competence in hedging of the Chinese English-major MA students, which provides significant implications for research and pedagogical practices of L2 pragmatic competence and academic writing.