7[2]Brown P, Stephen L. Politeness: Some Universals in Language Usage[M]. Cambridge: Cambridge University Press, 1987.62.
8[3]Olshtain E, Andrew D C. Apology: A speech-act set[A]. Wolfson N,Judd E. Sociolinguistics and Language Acquisition.[C]. Rowley, MA: Newbury House, 1983.22.
9[5]Holmes J. Sex difference and apologies: One aspect of communicative competence[J].Applied linguistics,1989,(10):209.