Abstract
1. Introduction
2. Literature Review
3. Method
4. Result
4.1 Total Corpus Analysis
4.2 Written and Spoken Corpus Data Analysis
4.3 Analysis of Certainty Degree Modal Use Trends
5. Discussion and Conclusion
5.1 General Modality Usage and Discourse Form
5.2 Epistemic Modality Preferences and Native Speaker Discrepancies
5.3 Influence of Native Language Modality
5.4 Sociolinguistic and Cultural Factors
5.5 Limitations
References