1Strunk Jr W, White E B, The Elements of Style [M]. New York: Macmillan Publishing Co. , 1972 : 65 - 77.
2Phillips E, Pugh D. How to Get a PhD [M]. Quoted in D. Silverman, Doing Qualitative Research : A Practical Handbook [M]. London: Sage Publications, 2000: 102-112.
3Thompson G, Ye Y. Evaluation in the Reporting Verbs Used in Academic Papers[J]. Applied Linguistics, 1991, 12 (4): 365- 382.