2Aronson, H.I. Towards a typology of verbal categories[A], In: Linda R. Wauch and Stephen Rudy (eds.). Current Issues in Linguistic Theory [C]. Amsterdam /Philadelphia: John Benjamings Publishing Company, 1991.
3Comrie, B. Aspect: An Introduction to the Study of Verbal Aspect and Related ProbIems[M]. CUP,1976.
4Freed. A.F. The Semantics of the English Aspectual Complementation [M]. Dordrecht: Reidel Publishing Company,1979.
5Langacker, R.W. Concept, Image, and Symbol: The Cognitive Basis of Gramma[M]. Berlin and New York: Mouton de Gruyter, 1990.
6Langacker, R.W. Foundations of Cognitive Grammar [M]. California: Stanford University Press,1991.
7Quirk,R. A Comprehensie Study of the English Language[M]. London: Longman,1985.
8Quirk,R. A Grammar of Contemporary English[M]. London: Longman., 1972. Cambridge: Cambridge University Press, 1976.
9Shefla Glasbey. Progressives, states and backgrounding [A]. In: Susan Rothstein (eels.). Events and grammar [C]. Great Britain: Kluwer Aeademie Publishers,1998.
10Smith, C.S. A theory of aspectual choice[J]. Language, 1983(3).