Abstract：With the rapid development of international economy, more and more people from all over the world communicate with each other. As a widely used communication means, business English correspondence plays an important role in international trade. Vague language, a language with flexibility and uncertainty, can play a unique role in business affairs if properly used in business English correspondence. Adaptation Theory is put forward by Verschueren, the theory helps people to study and explain pragmatics from a totally new perspective. Linguistic adaptation refers to the mutual adaptation between context and language. Based on Adaptation Theory, this thesis analyzes the employment of vague language in adaptation to mental world, physical world and social world. It is hoped that the current study would be conducive to further understand and master vague language in business English correspondence, offering some help for those who major in business activities to realize their communicative purposes.

　　　This thesis is divided into four chapters. Chapter one introduces the background of this study, Adaptation Theory, business English correspondence and the structure of this thesis. Chapter two presents vague language, previous studies on Adaptation Theory and vague language in business English correspondence. Chapter three analyses the employment of vague language in business English correspondence on the basis of Adaptation Theory. Chapter four is a conclusion, which summarizes this thesis and points out the limitations and suggestions for future study.        

Key words:  business English correspondence  adaptation theory  vague language

摘要：随着世界经济的快速发展，世界各地越来越多的人彼此交流。商务英语函电作为一种被广泛使用的沟通方式，在国际贸易中起着十分重要的作用。模糊语作为一种具有灵活性和不确定性的语言，合理的运用在商务英语函电中，能够发挥独特作用，从而促进商务活动的顺利进行。顺应论是由维索尔伦提出的，这一理论帮助人们从一个全新的视角理解和诠释语用学。语言的顺应体现为语言的使用语境和语言选择之间的相互适应。本文以维索尔伦的顺应论为理论基础，从模糊语顺应心理世界，物理世界和社会世界的角度分析商务英语函电中模糊语的应用。希望本文能有助于更好地了解和把握商务英语函电中的模糊语，帮助商务从业人员更好的实现其交际意图。

　　　全文共分为四个章节。第一章介绍本文的研究背景，顺应理论，商务英语函电以及本文结构。第二章介绍的是模糊语，前人对顺应理论和商务英语函电中模糊语的研究。第三章从顺应理论的视角分析模糊语在商务英语函电中的应用。第四章是结尾部分，该部分总结全文，并指出本文的不足和需要改进之处。

关键词: 商务英语函电；顺应论；模糊语