【Abstract】The public speech plays a very important role in social life.The paper intends to analyze the farewell speech of Harvards 28th president from the perspective of Hallidays two Meta-functions，in order to reveal their functional characteristics，and to find out the possible linguistic changes used to perform functions.By analyzing functional features of the Harvards 28th presidents discourse，we could find out the relationship between the choices of language modes and the meaning intended to express.

【Key words】discourse analysis; Systemic Functional Grammar; farewell speech

【作者簡(jiǎn)介】杜雪（1989-），女，漢族，吉林人，長(zhǎng)春理工大學(xué)外國(guó)語(yǔ)學(xué)院，英語(yǔ)語(yǔ)言文學(xué)專業(yè)，碩士二年級(jí)，研究方向：英美文學(xué)，亞裔文學(xué)。

1. Introduction

Discourse-based analysis came on the research agenda in the late 1970s， and the first person who uses the term‘discourseis Zellig Harris， in his article named“discourse analysis”published in magazine language in 1952. People show their different status， point of view， feeling， and attitude in language use because of their different social status， class status or economic status， different roles， and various situations. Discourse analysis is one of the most effective means to explore this phenomenon. Numerous studies have attempted to specify the meaning and function of discourse analysis， and it is almost impossible to have an agreed definition to DA and other fundamental issues of terminology.

2. The analysis of the speech

2.1 Analysis from the Perspective of Ideational Function

According to the table above， all the six processes are involved in the speech of? Harvards 28th president. From the analysis， we can find clearly that the most frequently used process in the? farewell speech of? Harvards 28th president is material process， followed by mental process， relational process， behavioral process， verbal process and existential process.

2.2 Analysis from the Perspective of Interpersonal Function

Apart from the function of expressing experiences，language can also express the speakers social status，attitude and inference about things.

2.2.1 Mood system

From the table 3，the distribution of declarative mood ranks first in the farewell speech of Harvards 28th president，with the percentage of 88.6% on the whole.By using declarative mood，the speaker tells the audience and hearer about the status of the act or thing.That is to say，the Harvards 28th president expresses her wishes， suggestion，hope to the students and the staffs.

2.2.2 Modality

According to the table 4， we can find clearly that in terns of the types of modality， modalization take a large proportion which greatly surpasses that of modulation. And these communicative functions can be related to a scale ranging from possibility to necessity， which is concerned with ability， permission and duty， likelihood and certainty， etc.

3. Conclusion

The paper figures on finding out the features of Harvards 28th presidents public speaking in the framework of Systemic-Functional Grammar.Transitivity，which is the main way to realizing ideational function.By using material process，the Harvards 28th president expresses what action she has made in the past eleven years，what events has took place and what she hopes the students to do.In the interpersonal function，the most frequent use is declarative mood.The public speaker acts as a giver of information，so the Harvards 28th president uses this type of mood introduce an entity about which she wants to make certain claims，so as to deliver her statements and give information to the vast audience.According to Halliday，reference is suggested to be the most commonly used one in all the cohesive means.The audience can understand the meaning of reference items by connecting the things inside or outside the context.

References：

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