4Bousfield, Derek. 2008. Impoliteness in Interaction [M]. Amsterdam: John Benjamins.
5Brown, P. S. C. Levinson. 1978. Universals in language usage: Politeness phenomena [A]. In E. N. Goody (ed.). Questions and Politeness: Strategies in Social Interaction [C]. Cambridge: Cambridge University Press.
6Brown, P. S. C. Levinson. 1987. Politeness Some Uni- versals in Language Usage [M]. Cambridge. Cam- bridge University Press.
7Caffi, Claudia. 1999. On mitigation [J]. Journal of Prag- matics 31: 881-909.