| 摘要 | 第1-5页 |
| Abstract | 第5-7页 |
| Table of Contents | 第7-9页 |
| List of Tables | 第9-10页 |
| List of Figures | 第10-11页 |
| List of Abbreviations | 第11-12页 |
| Introduction | 第12-16页 |
| Chapter One Literature Review | 第16-41页 |
| ·Definitions of Important Terms | 第16-31页 |
| ·Main Verb versus Auxiliary Verb | 第16-17页 |
| ·Modal Auxiliaries versus Auxiliary Verb | 第17页 |
| ·Longitudinal Study versus Cross-sectional Study | 第17-18页 |
| ·Language Acquisition | 第18-21页 |
| ·Language Attrition | 第21-31页 |
| ·Studies on Acquisition Sequence of English Auxiliary | 第31-36页 |
| ·Studies on Acquisition Sequence of English Auxiliary abroad | 第31-35页 |
| ·Studies on Acquisition Sequence of Auxiliary at Home | 第35-36页 |
| ·Studies on Attrition Sequence of English Auxiliary | 第36-40页 |
| ·Studies on Attrition Sequence of Auxiliary Abroad | 第37-39页 |
| ·Studies on Attrition Sequence of Auxiliary at Home | 第39-40页 |
| ·Summary | 第40-41页 |
| Chapter Two Methodology | 第41-56页 |
| ·Research Questions | 第41-42页 |
| ·Subjects | 第42-44页 |
| ·Instruments | 第44-52页 |
| ·Questionnaire | 第44页 |
| ·Test Paper | 第44-52页 |
| ·Pilot Study | 第52-54页 |
| ·Data Collection | 第54页 |
| ·Data Analysis | 第54-56页 |
| Chapter Three Results and Discussion | 第56-82页 |
| ·Features of English Auxiliaries in Attrition | 第56-69页 |
| ·Subjects' Performances on each Auxiliary | 第56-67页 |
| ·Attrition of Each Auxiliary Tested | 第67-69页 |
| ·Comparison of Attrition for Different Stages | 第69-72页 |
| ·Factors Affecting the Attrition of English Auxiliaries | 第72-80页 |
| ·Proficiency Level Prior to Attrition | 第74-75页 |
| ·Exposure to English | 第75-76页 |
| ·Sex | 第76-77页 |
| ·Length of Time since the Onset of Attrition | 第77-79页 |
| ·Age of Acquisition | 第79-80页 |
| ·Summary | 第80-82页 |
| Conclusion | 第82-86页 |
| Major Findings | 第82-83页 |
| Theoretical and Pedagogical Implications of the Study | 第83页 |
| Limitations | 第83-84页 |
| Suggestions for Future Research | 第84-86页 |
| References | 第86-90页 |
| Appendix Ⅰ外语能力保持情况调查问卷 | 第90-91页 |
| 英语助动词用法调查 | 第91-94页 |
| Acknowledgements | 第94页 |
