一、引言系统功能语法认为语言除了具有表达语言使用者对外部世界的经历和其内心世界的经验外(概念功能),它还具有表达讲话者和受话者之间的交际、社会角色定位的功能,即人际功能。人际功能主要的语法系统之一是语气系统,情态是语气系统中表现人际功能的主要手段。短剧 I. INTRODUCTION In addition to the experience of expressing language users’ experience of the external world and its inner world (conceptual function), the system functional grammar holds that the language has the function of expressing the communication between the speaker and the receiver and the social role of the speaker Function, that is, interpersonal function. One of the main grammatical systems of interpersonal function is the tone system, and modality is the main means of expressing interpersonal function in the tone system. Short play