7Brown, P & S C. Levinson. 1987[1978]. Politeness: Some Universals in Language Usage [ M]. Cambridge: Cambridge University Press.
8Bybee, J ,R Perkins & W Pagliuca. 1994. The Evolution of Grammar : Tense, Aspect, and Modality in the Languages of the Worm [M]. Chicago: The University of Chicago Press.
9Geis, M L & A M Zwicky. 1971. On invited inferences [J]. Linguistic Inquiry 2: 561-566.
10Grice, 1975. Logic and conversation [A]. In P Cole,& J Morgan (eds.). Syntax and Semantics 3: Speech Acts [C]. New York: Academic Press.
