| Acknowledgements | 第4-5页 |
| Abstract | 第5-6页 |
| 摘要 | 第7-13页 |
| Chapter One Introduction | 第13-16页 |
| 1.1 Background of the study | 第13-14页 |
| 1.2 Objectives of the study | 第14页 |
| 1.3 Significance of the study | 第14-15页 |
| 1.4 Layout of the thesis | 第15-16页 |
| Chapter Two Literature Review | 第16-26页 |
| 2.1 Key terms | 第16-19页 |
| 2.1.1 Code-switching | 第16-17页 |
| 2.1.2 Categories of code-switching | 第17-19页 |
| 2.1.2.1 Auer's classification | 第17-18页 |
| 2.1.2.2 Blom and Gumperz's classification | 第18页 |
| 2.1.2.3 Poplack's classification | 第18-19页 |
| 2.2 Theoretical Foundations | 第19-21页 |
| 2.2.1 Input hypothesis | 第19-20页 |
| 2.2.2 Discourse analysis | 第20-21页 |
| 2.3 Previous studies abroad and at home | 第21-26页 |
| 2.3.1 Empirical studies abroad | 第21-23页 |
| 2.3.2 Empirical studies at home | 第23-24页 |
| 2.3.3 Evaluation of previous studies | 第24-26页 |
| Chapter Three Methodology | 第26-32页 |
| 3.1 Research questions | 第26页 |
| 3.2 Research Design | 第26-32页 |
| 3.2.1 Participants | 第26-28页 |
| 3.2.2 Instruments | 第28-29页 |
| 3.2.2.1 Classroom observation | 第28页 |
| 3.2.2.2 Interviews | 第28-29页 |
| 3.2.3 Treatment | 第29-30页 |
| 3.2.3.1 Classroom observation | 第29页 |
| 3.2.3.2 Interviews | 第29-30页 |
| 3.2.4 Data collection and data analysis | 第30-32页 |
| 3.2.4.1 Classroom observation | 第30页 |
| 3.2.4.2 Interviews | 第30-32页 |
| Chapter Four Results and Discussion | 第32-50页 |
| 4.1 Differences about types of English teachers' code-switching in middle school classroom between eastern region and western region | 第32-37页 |
| 4.1.1 Types of English teachers' code-switching in East China's middle school classroom | 第32-34页 |
| 4.1.2 Types of English teachers' code-switching in West China's middle school classroom | 第34-35页 |
| 4.1.3 Differences about types of English teachers' code-switching in middle school classroom between eastern region and western region | 第35-37页 |
| 4.2 Differences about factors influencing English teachers' code-switching in middle school classroom between eastern region and western region | 第37-50页 |
| 4.2.1 Factors influencing English teachers' code-switching in East China's middle school classroom | 第38-42页 |
| 4.2.1.1 Students' English proficiency | 第38-39页 |
| 4.2.1.2 Teachers' teaching beliefs | 第39-40页 |
| 4.2.1.3 Class time | 第40-42页 |
| 4.2.1.4 Teacher's evaluation system | 第42页 |
| 4.2.2 Factors influencing English teachers' code-switching in West China's middle school classroom | 第42-48页 |
| 4.2.2.1 Students' English proficiency | 第43-44页 |
| 4.2.2.2 Teachers' teaching beliefs | 第44-45页 |
| 4.2.2.3 Class time | 第45-46页 |
| 4.2.2.4 Teacher's evaluation system | 第46页 |
| 4.2.2.5 Cultural influence | 第46-48页 |
| 4.2.3 Differences about factors influencing English teachers' code-switching in middle school classroom between eastern region and western region | 第48-50页 |
| Chapter Five Conclusion | 第50-54页 |
| 5.1 Major findings | 第50-51页 |
| 5.2 Implications | 第51-52页 |
| 5.3 Limitations and suggestions for future studies | 第52-54页 |
| References | 第54-58页 |
| Appendixes | 第58-66页 |
| Appendix Ⅰ:Transcriptions of code-switching in English classroom | 第58-62页 |
| Appendix Ⅱ:Transcriptions of interviews | 第62-66页 |
