Part 1A Study on English Discourse Markers1 Abstract1 Chapter 1Introduction4 Chapter 2Theoretical Basis14 Chapter 3The Textual Function of Discourse Markers Under the Framework of Relevance Theory26 Chapter 4Application in Teaching EFL Speaking56 Chapter 5Conclusion77 References81 Part 2Investigating the Features of Teacher Talk in the Chinese EFL Context87 Abstract89 Chapter 1Introduction91 Chapter 2Review of Literature99 Chapter 3Research Methodology115 Chapter 4Presentation of Findings124 Chapter 5Discussion143 Chapter 6Conclusion155 References158 Appendix ⅠConsent Form for the Students or Their Parents/ Guardians163 Appendix ⅡTranscription Conventions165 Appendix ⅢTranscription of VideoRecordings167 Appendix ⅣTranscription of Teachers Interviews181 List of Abbreviations186