2。4 Previous research on vague language in business correspondences 

     The research of vague language in business letters is not universal。 Blundel(1998) noted that accuracy and clearness have always been used in business communication。 From his aspect, we know that the vague language is always considered to be avoided in business communication。 In addition, Blundel(1998) believed that communication is pervasive and it can be used in all areas of business including business meetings, business letters etc。 Channell(2000) noted that one of the functions of vague language is to strength the persuasiveness of communication。 Combining the two scholar’s opinions, we can get the conclusion that the use of vague language is one of the significant characteristics of business correspondence writing。 So the research on vague language in bad-news business should not be ignored by scholars。 In 1999, Sun Xiangsheng and Gong Yanxia discussed the use of vague language briefly in Modern Business Communication。 Cheng Tongchun(2000) paid more attention to the concept of vague language。 And he attempted to study the pragmatic functions of vague language in business correspondences。 He put forward three pragmatic functions of vague language in business letters。 Hu Zhiwen(2002) paid his attention to the influence of vague language in business letters。 Due to the negative and positive effects of vague language, he stated that the writer should consider carefully when use the vague language in business letters。 Liao Ying(2004) pointed out three reasons for employing the vague language in busiess letters including: to show politeness, to realize self-production and to show your attitudes。 Zhou Wei(2004) combined the use of vague language with the Relevance Theory。 Chen Ruxin(2008) studied the vague language in bad-news business letters from the perspective of pragmatics。 Jiang Yuchao(2012) studied the application of vague language in business English correspondence from the perspective of adaptation。 Besides, Zhang Lin(2014) and Xie Huiru(2015) also adopted the adaptation theory to study the vague language in business letters。 From above, we know studying the vague language in business letters has been a tendency nowadays。