1Halliday M. A. K. An Introduction to Functional grammar[ M ]. London :Edward Arnold, 1985, 1994/2004. 65 -86.
2Mathesius,V. On the Potentiality of the Phenomena of Language[ A]. inJ Vachek ( Ed. ) A Prague School Reader in Linguistics[ C ]. Blooming-ton ,Ind : Indiana University Press, 1964.