Literature Review This chapter consists of three sections. Section 2.1 gives a brief explanation of diplomatic vagueness and section 2.2 introduces adaptation theory. Section 2.3 provides a general review on diplomatic vagueness about Sino-US trade war between China and America from the perspective of adaptation theory. 2.1 Brief explanation of diplomatic vagueness Language communication is a complex linguistic phenomenon, in which vague language plays an important role (Channell 1994:28). Vagueness language is a special language used by people to achieve a certain communicative purpose in a specific environment, and its manifestation is "I believe... , "I think..." , "about", "approximately"... . Diplomatic vagueness is widely used in foreign affairs, such as foreign speeches, treaties, agreements, business negotiations, press conferences, summits, military conflicts, etc. Li Rui (2012) mentioned that, in diplomatic activities, due to the speaker's position and the strategic need of language expression, as well as the estimation of various potential factors, the speaker often deliberately uses some vague words to ensure the speech is safe, rigorous, polite, flexible and efficient, so as to solve diplomatic problems and achieve the best communicative effect.The diplomatic rhetoric used in these diplomatic activities is bound to safeguard the sovereignty, interests, dignity and status of the state. As a language phenomenon widely used in diplomatic activities, vague language has far-reaching practical influence and its existence is diversified. Common diplomatic vagueness includes words with fuzzy meanings, sentences with fuzzy meanings, hedges and euphemisms(Cong Jiaolong, 2012). Firstly, ambiguity at the lexical level is represented by nouns, adjectives, adverbs, etc, such as ”understanding”, ”effective”, ”deeply”. Secondly, the fuzziness at the syntactic level is reflected in grammar or structure. For example, diplomats use ”not support” instead of ”oppose” in foreign affairs for that using negative sentences to give the other person face. Thirdly, ”some”, ”hardly”, ”i think”,etc, these words works as hedges in diplomatic affairs for they would limit the vagueness of fuzzy words. Fourthly, diplomatic euphemism often reflects a kind of politeness and respect. For example, the term "developing country" is often used in diplomatic affairs to refer to a country that is temporarily backward economically but has the potential to rank among developed countries after development. This euphemism reflects the temporary economic backwardness of the country(Cong Jiaolong, 2012). 2.2 Adaptation Theory The theory of adaptation was proposed by Verschueren, a Belgian linguist, in 1999. He believes that the use of language is a process of continuous selection of language, whether the choice is conscious or unconscious, whether it is due to internal reasons or external reasons. The reason why language users can make all kinds of appropriate choices in the process of using language is that language has variability, negotiability and adaptability(Liu Hongwu, 2013). The variability of language means that language has a series of alternative possibilities. Negotiability means that all the choices are not made mechanically or strictly in accordance with the relationship between form and function, but on the basis of highly flexible principles and strategies. Adaptability refers to the fact that language allows its users to be flexible from alternative projects so as to meet the needs of communication. Among these three characteristics, adaptability is the core, variability is the basis, negotiability is the principle, and the key of adaptability is adaptability to context. Verschueren divides context into communicative context and linguistic context. Communicative context includes language user, physical world, social world and psychological world. Linguistic context includes cohesion, intertextuality and sequence(Liu Hongwu, 2013). 2.3 Related empirical studies 2.3.1 Previous studies on diplomatic vagueness Now more and more Chinese and foreign scholars are focusing on vague language and dabbling in many fields. Recent years, the vagueness in diplomatic language has been well studied. Huang Shan and Yi Chunyan(2018) mentioned in their paper that politicians do not obey the Cooperative Principle, frequently conveying indirectly their meanings by using vague expressions for various political purposes. Zhang Fang(2011)confirmed that from the perspective of Cooperative Principle, diplomatic vagueness violates quality maxim and quantity maxim, so as to reach certain communicative effects and from the perspective of Politeness Principle, diplomatic vagueness may obey tact maxim, agreement maxim, approbation maxim and sympathy maxim. Furthermore, Xu Bo and Guo Zhengmin(2010) thought that employing pragmatic vagueness in diplomatic language can help a diplomat to gain foremost national interest and win honor for his/her motherland. Although vagueness has been discussed in many fields including diplomatic affairs, it is still of great research value to study fuzzy language in specific diplomatic corpus. 2.3.2 Previous studies on vagueness from the perspective of adaptation theory Because of the special variability, negotiability and compliance of adaptation theory, it has been widely used in the study of fuzzy language. Researchers can analyze the pragmatic functions of fuzzy language from its different characteristics and in recent years, researchers mainly study fuzzy language from the perspective of compliance while the research dimensions are different. Chen Chen Lei Yan (2017) focused on the negotiability of adptation theory, he thought that diplomats would often use fuzzy strategy to express one#8217;s point of view or attitude. On the one hand, they could achieve the principle of polite and not to hurt other#8217;s feeling; on the other hand, they could protect them and make excuses for the behavior. And Guan Ke(2010) emphasizes the analysis from the linguistic context of adaptability. He mentioned in his thesis that people are not only part of the context, but also actively adapt to the context. In the process of communication, under the guidance and regulation of contextual awareness, the speaker makes appropriate language choices to adapt to the changing context, which fully reflects the characteristics of linguistic coherence and human subjective initiative, and also provides a possible theoretical perspective for the selection of pragmatic ambiguity strategies in the diplomatic environment. Although linguistic context of compliance of adaptation theory has been discussed, it is still of great value to study specific material from another communicative context of compliance. 2.3.3 Previous studies on Sino-US Trade War between China and America With the start of the Sino-US trade war, the relations between China and America have gradually changed. Many researchers have conducted analysis and research on the Sino-US trade war from game theory and approach perspective in the past year. Jia Kang Ou Zhichun (2018) mentioned in Leadship Science that China and the United States compete with each other for their own interests and strive to achieve a game equilibrium. This equilibrium point may not be the optimal interest point of each country, but it must be the best advantage that both countries can achieve in this trade conflict. This game theory is based on the calculation of the maximization of their own interests. And Yan Bing Zhang Hui(2018) made research on diplomatic language about Sino-US trade war from the point of approach theory. They thought the approach theory is an effective discourse strategy to realize the legitimacy of the speaker or to strengthen the illegality of the other party. In order to implement the principle of peaceful coexistence in China, this paper will analyze the rhetoric of the ministry of foreign affairs on Sino-US trade war from the perspective of adaptation theory. In this paper, it focuses on the issue of Sino-US Trade War between China and America from the perspective of adaptation theory. The trade war between China and the United States has been brewing for nearly a year, during which both sides have been trying to maintain their respective interests. How to maximize our respective interests without upsetting the balance of the world economy has become the top priority of our foreign ministries. At this point, this essay would choose the language used by a foreign ministry spokesperson at a regular press briefing on the trade war between China and the United States to analyse how diplomats use vagueness to balance the peaceful global economic climate and national interests and economic security. Content Abstract Introduction 1.1 Research background 1.2 Research purpose and structure of the thesis Literature Review 2.1 Brief explanation of diplomatic vagueness 2.2 Adaptation Theory 2.3 Related empirical studies 2.3.1 Previous studies on diplomatic vagueness 2.3.2 Previous studies on vagueness from the perspective of adaptation theory 2.3.3 Previous studies on Sino-US Trade War between China and America Methodology 3.1 Research questions 3.2 Data collection 3.3 Data analysis Results and discussion 4.1 Linguistic adaptation of diplomatic fuzziness 4.2 Pragmatic functions of diplomatic fuzziness Conclusion 5.1 Major findings 5.2 Research limitation and suggestion for further study Reference Reference [1] Steve Rolf,John Agnew. Sovereighty regimes in the South China Sea:assessing contemporary Sino-US relations. Taylor Journal.2016:249-273 [2] Chen CHEN, Lei YAN. A study of pragmatic vagueness in diplomatic language from the perspective of adaptation theory[J]. Science and Engeering Research Center. 2017:143-147 [3] 徐波，郭政敏.On pragmatic vagueness in diplomatic language[J].Read and Write Periodical.2010,(03):25-26 [4] 张芳.A pragmatic pproach to vagueness in diplomatic language[J].Overseas English.2011,(05):257-259 [5]黄姗，易春燕. Analysis of vagueness in diplomatic language from the politeness principle[J]. Overseas Language. 2018,(11):226-227 [6]冉永平，方小国.语言顺应论视角下反问句的人际语用功能研究[J].现代外语.2008,(04):351-359 [7]蔡英英，王飞.对外交模糊语的语用分析[J].怀化学院学报.2011,(11):65-68 [8]丛娇龙.基于顺应论的外交模糊语语用功能分析[J].科技信息.2012,(32):565-566 [9]刘洪武.动态顺应视域下外交辞令中的模糊语言研究[J].长春工程学院学报（社会科学版）.2013,(02):62-65 [10]张娜，姚苑蕾.从语用角度分析外交话语的模糊性[J].开封教育学院学报.2013,(05):17-19 [11]朱雅丽.顺应论视角下的跨文化交际语用失误研究[J].黑龙江高教研究.2014,(09):174-176 [12]赵春霞.顺应理论视角下英语新闻中的模糊现象[J].新闻战线.2016,(16):31-32 [13]刘建飞.新时代中国外交战略中的中美关系[J].美国研究.2018,(02):9-18