| 摘要 | 第5-6页 |
| ABSTRACT | 第6页 |
| List of Abbreviations | 第7-12页 |
| Chapter 1 Introduction | 第12-17页 |
| 1.1 Research Background | 第12-13页 |
| 1.2 Purpose of the Study | 第13-15页 |
| 1.3 Research Questions | 第15-16页 |
| 1.4 Layout of the Thesis | 第16-17页 |
| Chapter 2 Literature Review | 第17-32页 |
| 2.1 Previous Studies on Auxiliaries | 第17-27页 |
| 2.1.1 Defrinition and Classification of Auxiliaries | 第17-23页 |
| 2.1.2 Previous Studies on the Frequency Changes of Modal Auxiliaries | 第23-27页 |
| 2.2 Previous Studies on Grammaticalization | 第27-32页 |
| Chapter 3 Research Methodology | 第32-43页 |
| 3.1 Corpora Used in this Study | 第32-40页 |
| 3.1.1 Advantages of Corpus-based Approach in Lexico-grammatical Studies | 第32-33页 |
| 3.1.2 The Brown Family Corpora | 第33-37页 |
| 3.1.3 COCA and COHA Corpra | 第37-40页 |
| 3.2 Software Used in this Study | 第40-42页 |
| 3.2.1 Perl 5.10 | 第40-41页 |
| 3.2.2 Log-likelihood and Chi-square Calculator 1.0 | 第41-42页 |
| 3.3 Procedures for Data Collection and Analysis | 第42-43页 |
| Chapter 4 Data Analysis and Discussion | 第43-66页 |
| 4.1 Distribution of Semi-auxiliaries in the Brown Family Corpora | 第43-57页 |
| 4.1.1 A Diachronic Comparison on the Changes of Semi-auxiliaries in AmE | 第43-46页 |
| 4.1.2 A Diachronic Comparison on the Changes of Semi-auxiliaries in BrE | 第46-49页 |
| 4.1.3 A Synchronic Comparison on the Frequency of Semi-auxiliaries between AmE and BrE | 第49-53页 |
| 4.1.4 Cross-referencing by COCA and COHA | 第53-57页 |
| 4.2 Tentative Explanations for the Frequency Changes | 第57-66页 |
| 4.2.1 Language-internal Factors | 第57-61页 |
| 4.2.1.1 Grammaticalization | 第58-60页 |
| 4.2.1.2 Subjectification | 第60-61页 |
| 4.2.2 Language-external Factors | 第61-66页 |
| 4.2.2.1 Americanization | 第61-62页 |
| 4.2.2.2 Democratization | 第62-63页 |
| 4.2.2.3 Colloquialization | 第63-66页 |
| Chapter 5 Conclusion | 第66-72页 |
| 5.1 Major Findings of the Study | 第66-68页 |
| 5.2 Pedagogical Implications | 第68-69页 |
| 5.3 Limitations and Suggestions for Further Studies | 第69-72页 |
| References | 第72-76页 |
| Appendix Programme for Semi-auxiliaries Extraction | 第76-84页 |
| Acknowledgements | 第84-85页 |
| Resume | 第85页 |
