“参照语料库可以是多种文体的混合语料,而且越大越好｡……”(Mike Scott,2016:112)｡本文以BaREnloB 为参考语料对比探析了中国英语专业学生语料库WECCL(1.0)四个年级大学生议论文中情态序列使用的年级趋向｡研究发现:1)方差分析与稳健性检验表明,BIS､LOG_L 与LOG_R 各指标基本呈现显著的年级差异,类认知序列除外｡2)方差分析均值图发现:就认知序列而言,BIS 与LOG_L 随年级上升而上升,在三年级达到高峰值,四年级跌入低谷;而LOG_R 随年级上升而缓步上升,四年级达到高峰值;就义务序列而言,BIS 与LOG_L 随年级上升而逐步下降,但在二年级有些反复,出现高值;而LOG_R 随年级上升稳步向下,时急时缓;而在类认知序列方面,尽管BIS､LOG_L 与LOG_R 的变化趋势基本趋于一致,随着年级的上升基本平缓不动,稍有波动,只在四年级时达到最好,但并不存在显著的年级区别｡3)参数检验与非参数检验结论基本不相同,有些结论完全相反｡

“Reference corpus can be a mixture of different genres, and the bigger the better ......” (Scott,2016:112). With BaREnloB as the reference corpus, this paper makes a comparison of the grade trends of the epistemic modality sequences used in the argumentative essays in Written English Corpus of Chinese Learners 1.0(WECCL 1.0). Research findings reveal:1) whether through variance analysis or robustness test, all BIS,LOG_L and LOG_R basically show significant grade differences except for the analogue epistemic sequences. 2) Means plots of variance analysis suggest that, as to epistemic sequence, both BIS and LOG_L rise with grade and reach the peak in the third grade, and fall to the lowest in the fourth grade, while LOG_R goes up slowly with grade, reaching its peak in the fourth grade; As to the dynamic sequence, BIS and LOG_L are gradually decreasing with the rise of grade and there are reversed and high values in the second grade while LOG_R goes down in riptide and slack tide; Regarding the analogue epistemic sequences, there exists no significant grade difference although BIS, the LOG_L and LOG_R all remain basically flat and consistent as the grade rises, and sometimes fluctuates slightly, only to attain the best in the fourth grade. 3) The results of parametric and non-parametric test are fundamentally different, and some conclusions are completely opposite to each other.