（ 2011 届）

题 目 模糊限制语视角下的女性话语特征分析

学 院 外国语学院

专 业 英 语

班 级 英 语071

学 号 200736635122

学生姓名 夏菁菁

指导教师 周红

完成日期

教 务 处 制

二o 一 一年 五 月 十 八 日

Analysis of Characteristics of Female Utterance from the Prospective of Hedges

A Thesis

Submitted in Partial Fulfilment of the Requirement for the B.A. Degree in English Language and Literature

By

Xia Jing-jing

Supervisor: Zhou Hong

Academic Title: Professor

College of Foreign Languages

May 18, 2011

诚 信 声 明

我声明，所呈交的论文(设计)是本人在老师指导下进行的研究工作及取得的研究成果。据我查证，除了文中特别加以标注和致谢的地方外，论文(设计)中不包含其他人已经发表或撰写过的研究成果，也不包含为获得＿＿＿＿＿＿或其他教育机构的学位或证书而使用过的材料。我承诺，论文(设计)中的所有内容均真实、可信。

论文(设计)作者签名： 签名日期： 年 月 日

授 权 声 明

学校有权保留送交论文（设计）的原件，允许论文（设计）被查阅和借阅，学校可以公布论文（设计）的全部或部分内容，可以影印、缩印或其他复制手段保存论文（设计），学校必须严格按照授权对论文(设计)进行处理，不得超越授权对论文（设计）进行任意处置。

论文(设计)作者签名： 签名日期： 年 月 日

摘　要

作为模糊语言家族的一个组成部分，模糊限制语是其中最普遍、最典型的、最具研究价值的语言现象。研究表明，与男性相比，女性更倾向于高频率地使用模糊限制语，因此，模糊限制语已成为女性话语的一个重要特征。本文首先以2009年，2010年奥斯卡奖项以及2010年MTV这三场国际性影视颁奖典礼上女性获奖感言为语料，着重分析获奖感言中女性使用模糊限制语的原因：生理因素，心理因素，言语话题需要，工作性质，探究模糊限制语在女性话语中的语用功能，合理地使用模糊限制语可以使得会话更加精确，同时展示说话人的礼貌，保护自我，展示自我，使读者了解到模糊限制语在女性话语中发挥着不可忽视的意义。

关键词：模糊限制语; 女性话语; 原因; 语用功能

Abstract

As a part of the fuzzy language, hedges are the most common, typical, and of most worthy researching in all of the language phenomena. It shows that female, compared with male, tend to make use of hedges frequently. Therefore, hedges have become a distinguishing feature in the female utterance. Based on the females’ speech on several award presentation ceremonies of international film and television circles, this thesis emphatically looks into the factors of hedges in the female utterance, namely physiological factor, psychological factor, the factor of utterance topic, and the factor of working environment, analyzes the pragmatic functions of hedges in the female utterance .The appropriate use of hedge in female utterance is able to achieve the relative precision of communication, show courtesy, protect herself and present herself, which makes readers aware of the hedges’ greater influence in the female utterance.

Key Words: hedges; female utterance; factors; pragmatic functions

Contents

1. Introduction……………………………………………………………………....1

2. Hedges…………………………………………………………………………….2

2.1 The Definition of Hedges………………………………………………………2

2.2 The Classification of Hedges……………………………………………...........2

2.3 The Structure of Hedges………………………………………………………...3

3. Analysis of Material ……………………………………………………………....4

4. The Factors for Hedges Used Frequently in Female Utterance………………..5

4.1 Physiological Factor…………………………………………………………….6

4.2 Psychological Factor………………………………………………………........6

4.3 The Factor of Utterance Topic ……………………………………………….…7

4.4 The Factor of Working Environment……………………………………………8

5. The Pragmatic Functions of Hedges……………………………………………...9

5.1 The Relative Precision of Communication……………………………………..9

5.2 Showing Courtesy……………………………………………………………..10

5.3 Self-protection & Self-presenting………………………………………..……11

6. Conclusion………………………………………………………………………...12

Bibliography………………………………………………………………………...13

Acknowledgements…………………………………………………………………14

1 Introduction

a cybernetics expert of the University of California in the United States in 1965, published a thesis Fuzzy Sets on the magazine of Information and Control in proposing the famous fuzzy theory, which was of epoch-making significance of the science age. In 1972, an American linguist, G. Lakoff, announced a thesis named Hedges: a study in meaning criteria and the logic of fuzzy concepts. It is the first time to bring about the term Hedges and definite it “words whose job is to make things fuzzier or less fuzzy”. In 1975, Lakoff pointed out that some language characters appear more frequently in female utterance than in male’s. Then he called this language phenomenon women’s language or features. In fact, hedges are one of the distinct characters among the women’s language or features.

Professor Wu Tiepin launched a paper First Exploration of Vague Language on the forth issue Foreign Language, marking the beginning of vague language in China. Since a number of language linguists have engaged in the study, vague language has become an emerging and frontier science. With the development of fuzzy linguistics at home and abroad, hedges are also stepping into a new stage both in theory and in application. However, although many Chinese linguists do a lot work of the hedges appliances, hedges in female utterance characters are shortage of formation of in-depth and systematic research.

In these years, lots of linguistics are tied up with female from the aspect of hedges. Shui Miao (2008) analyzed the functions of exactness, interpersonal relationship ,flexibility and misconception of gender differences on hedges, and also discussed the reasons of hedges in female utterance. But she failed to connect the practical materials with hedges. Zhang Xiaohui (2009) owes this character to women’ low society status, which appears to be far more than to explain this phenomenon completely. Taking the example of Pride and Prejudice, Wang Peng and Sun Feiran (2009) discussed the pragmatic functions and reasons of hedges in female utterance and stated that hedges have interpersonal coordination, dissemblance and protection as well as refinement and courtesy functions. It seems lacking in enough evidence for women frequent use of hedge in practice. If we want to search into the use of hedges in female utterance, the best method is to combine the theory with oral practice.

2. Hedges

2.1 The definition of hedges

As for the definition of hedges, different language linguists have different explanations. The term, hedges, was firstly defined as “words whose job is to make things fuzzier or less fuzzy” by Lakoff in 1972.The notion of hedges is just some uncertain conception or restrictive phases on the discipline pragmatics and discourse analysis in Cristal’s (1997:170) Modern Linguistic Dictionary .Verschueren (1999:193) held the view that hedges limited the prepositional content directly, namely evaluating preposition attitudes, congnition or proof attitudes in the direct way, at the same time showing metapragmatic awareness. Weinreich(1996) called hedges metapragmatic operation language, such as true, real. Yule (1996) defined “the cautious comprehending expression of how are the words understood ” in his book Pragmatics, like “as far as I know” ,this word providing certain information for us.

Personally, the author prefers the definition of hedges given by Li Qianju in his book Vague Semantics Introduction: hedges are attached to the clear meaning words or expressions, which can change original, certain conception to vagueness. As a matter of fact, hedges are not only words, phases, but also some composite structure and minor sentence . We can totally call them hedges.

2.2 The classification of hedges

According to different standards, there are a variety of classifications of hedges that linguists put forward. Four types appears originally in reseach: some adjectives and adverbs; like some suffixes –ish, -likely, -ly , once they are added to words, these words may become hedges; some words indicate speakers’ hesitation or uncertainty, acting as adverbials of manner or adverbials of degree; when someone expresses oneself, he /she makes use of sentence structure in order to show more polite. Kasper (1981) regarded hedges as downgrader: face marker, such as “please”, “could”; understater, like “a little”; subjectivizer,like “i’m afraid”; downtoner, such as “probably” , “maybe”; cajoler, like “you know”; appealer, like “right”; hesitation marker, like “well”; limiter, like “this weekend”.

In our country, according to He Ziran’s research, hedges consist of approximations and shields. From the board semantic characters, Chen Linhua (1994) divides hedges into five types: degree, range, quality, quantity and manner. Semantic hedges and pragmatic hedges under the degree of hedges depending on contexts make up of hedges proposed by Gao Xiaofang and Zhang Qin. What’s more, Zhao Yinglin classifies hedges of science and technology language into three parts: accuracy-oriented hedges, author-oriented hedges and reader-oriented hedges in accordance with hedges functions and restrictive range.

However, so far the most influential and widely recognized one is proposed by E. F. Prince and his colleagues, J. Frader and C. Bosk from the point of pragmatics.

Adaptors

Approximators

Rounders

Hedges

Plausibility shields

Shields Attribution shields

2.3 The structure of hedges

Approximators can alter the original meaning of discourse structure, or make some changes of the original words to some extend based on the practical situation, or give a fluctuating range to the original words. Adaptors are those that can reveal the true extent of differences in discourse, while rounders are those that limit fluctuating range. On the contrary, shields don’t change the original meaning of discourse structure. It is just addition of an explanation which makes original affirmative tone towards relaxation. Plausibility are those speakers pluzz or doubt the theme, while shields shows speakers’ uncertainty of the theme, but it borrows the third person’s opinion in order to express oneself indirectly.

3 Analysis of Material

This paper collects the females’ speech on the ceremony of 2009~2010 Oscar and 2010 MTV and analyzes hedges among these materials. Relatively speaking, these prizes are enjoying a high reputation all the times, a reflection American films’ development, even having great effect on many countries’ art in the world. Hence, annual award ceremony is considerably holy in numerous movie lovers’ heart.

From the data of chart, we can learn that hedges take up quite a few of proportion in their speech. In addition, compared with male, female are inclined to use hedges at a higher rate. In 2009 Oscar, the rate of women using hedges is 2.75% higher than the male’s. Furthermore, in 2010, the gap rate increases by 6.55% on Oscar ceremony, while the rate of using hedges in female utterance on 2010 MTV ceremony gets to 13.51% , 7.45% higher than male’s.

4. The Factors for Hedges Used Frequently in Female Utterance

From the chart analysis above, we acknowledge that the phenomenon female tend to use hedges at a higher rate actually exists. As is known to us, there are many reasons for the present situation. On one hand, it could trace back to women’ physiological and psychological factors. On the other hand, from the view of social development, it may regulate the language development. In short, nature, culture and social, all of these altogether shape the character in female utterance. Many linguists regard the social status as the main reason in recent years’ research. That is to say, women’ lower social status than men’ leads to the high rates in female utterance. Nevertheless, in view of the public figures’ high social status involved in the materials, we don’t expound the social status factor any more.

4.1 Physiological factor

In terms of physiological mechanism, women’ physiological mechanism is more excellent than men’, so women are good at expressing themselves and possessing American Californian Institute of Technology, revealed the secrets of brain hemispheres. After that, a considerable part of researches show that women’ brain develops one year and a half to two years earlier than men’, especially the early development of brain left hemisphere control of language center. Therefore, women have the advantage of communication. “…on thinking, women’ imaginable thinking provides unique condition for women usage in expression of feeling.” There exists gender difference of development speed and level of brain hemisphere specialization function. Women’ left brain grows earlier, and levels are higher, whereas men’ right brain grows earlier, and levels higher. This accounts for male’s better special ability and female’s better language ability.

Through the comparison of Sandra Bullock-- Jeff Bridges，Kate Winslet-- Sean Pen and Kristen Stewart—Robert Pattison, it can be proved that female are inclined to use more hedges, and that women use diverse hedges words , while men use plain hedges words. Therefore, hedges in female utterance have the natural condition for more frequent use. Getting to the bottom of the matter, women’ advantageous language ability elaborates the character.

4.2 Psychological factor

From psychology mechanism, the female’s growth environment makes feeling deeper, and more meticulous. Doctor Caroline, the professor of Institute of Pedagogy in Harvard, disclosed in her book the female stance in the male life cycle (1982): Female’s main character is to care and love others, pay attention to delicate feeling in the communication relationship. At the same time, in allusion to the Freudian mental theory” male suppresses female”, she points out in a sharp way: caring, loving people and emotion aren’t female’ flaw, but the superiority by the comparison of male.

Female and male get different gender identification in the growth process since the childhood. Psychologically, this leads to more emotion enlightenment for female so that it develops in the direction of the female role. It isn’t strange that female would pay more attention to the way they express. There is no doubt that women are tending towards modesty, patience, and cooperation in the communication. Even if they have different opinions, they will not express themselves directly to show their personality on purpose, but deliver themselves implicitly. Thus, in order to get balance of mental and emotion, reach an aim of communication, and obtain the effect of politeness, women will attach more importance to hedges properly. For instance,

(1) Did I really earn this or did I just wear you all down?-- Sandra Bullock

In this sentence, the prize-winner asks a question. “我是真的凭本事赢得了这个奖，还是你们被我烦死了（颁个奖了事）？”. It shows the winner lacks a little bit confidence. The use of “really” and “just” emphasizes the question tone, which shows the person’s mental inadaptability or modesty and cooperation to convey feelings obscurely.

(2)“I feel very fortunate to have made it all the way from there to here.”-- Kate Winslet

“I feel”, a plausibility word, embodies the winner’s thoughts in the deep heart so that it shows the mental and feelings cognition of oneself about hedges in female utterance. “Very” proves the winner’s strong mental reaction, stating “表演之路一路走来，感觉自己是非常的幸运”. The two words imply the winner’s excitement of the Oscar prize in that the winner knows it difficult to achieve this award.

4.3 The factor of utterance topic

Xu Lisheng (1997) believed that women always talk about interpersonal affairs, but men are opposite because they avoid exposing themselves and keep some distance with the communication situation. The hottest topic of women is livelihood and affection, which has close connection with their status, job, social reputation, unique female character etc. Some topics--dressing, love, family, life affairs, experience, thoughts, and inspiration-- are permanent in the women’s spoken language community. All of these can not separated with female inborn affection and thinking. When women chat about these topics together, communicators can keep an equal, harmonious and coincident relationship.

In general, people often talk about interesting private topics. There is no denying that the difference of interest results in different talking content. It has been evident that women prefer to individual feelings and relations with others, and that men always talk about same interesting activities, like sports, job, spare time activities and common memory. Women’s topics need more tactful, and then hedges are the tool of making these topics natural. Whether confining oneself or evaluating others not, hedges are indispensable in these private topics.

（3）“And Meryl, you know what I think of you and you are such a good kisser.”-- Sandra Bullock

This sentence is involved in the winner and Meryl’s “kissing” matter on the award ceremony of American film critics. It belongs to evaluation topic that is not convenient for public. The winner only uses “you know what I think of you”,” such” to recall Meryl’s memory for the effect of communication euphemism.

（4）“Not enough time ,so I would like to thank what this film is about for me which are the moms that take care of the babies and the children no matter where they come from.”-- Sandra Bullock

Here the topic is about the winner’s family. “I would like” and “about” reflects the winner’s eager to be thankful for everything the film brings about, not only the best leading actress award, but also others: experience, hardship as well as the support from family y. When women talk about life and affection like family, they always make use of the plausibility “I would like” to vague own personal thoughts.

4.4 The factor of working environment

Nowadays, human interaction has become an indispensable means of communication in the modern society. Importantly, the communicating ability is essential to the nature of success. The human interaction consists of group, language, purpose, bi-direction. As a member of society, the speaker’s occupation and identity determine their requirements of language from the interpersonal view. The speaker’s communication quality affects the efficiency of their work to a great extent. For example, scientific research staff can’t use such vague words as “about”, “quite”, “maybe”, because of higher precision in science fields. On the contrary, in order to avoid conflict and show courtesy to achieve the desired effect of expression, public servants will use the hedges frequently in a euphemistic way.

Hence, the application of hedges is determined by the dependence on the nature of job. Due to all of the people on the award ceremony in the paper being female public figures, their job nature enlarges the impact of their words. No doubt, they will make the most of use of hedges in their speech for personal publicity, charm and expression flexibility.

（5）“And I want to acknowledge my fellow nominees, these goddesses. I think we all can’t believe we’re in a category with Meryl Streep at all.”-- Kate Winslet

As the prize-winner in this sentence mentioned, she’s in honor of be part of Best Leading Actress Meryl Streep(2007, Oscar Best Leading Actress) groups. The academy award is the most sparkling entertainment ring. It’s very natural to introduce herself with so many hedges.

（6）“‘Twilight’is really awesome. And I agree.”-- Kristen Stewart

Like the example above, it is closely related to the charming film. In fact, it results from their nature of job. One thing, “really” put stress on the excellent quality of the film. Another thing, it suggests viewers keep eyes on the films. To be frank, they give the films and work team publicity absolutely. In all, the two similar examples are determined by their job in the film circle.

5. The Pragmatic Functions of Hedges

Lakoff held that hedges are the most worthy doing research because of their many pragmatic aspects of function. Therefore, hedges have its specific pragmatic functions in this award ceremony.

5.1 The relative precision of communication

“As long as the vague language is under conditions, it’s able to get the exact meaning. That is absolutely right on the description of objective facts. ” (cited by Wang Yongzhong 2003:59) In a sense, hedges can play the role of accuracy.

Hedges appear to be vague, unclear, but it was not necessarily bad. Sometimes we have to speak clearly, while there are some occasions we must be vague in the communication. Owing to objective or subjective reasons, people will consciously or unconsciously use hedges.As Russell (1923) said, the vagueness of the objective world is surrounded by the world’s mobility, indivisibility and continuity. A lot of matter, phenomenon and characteristics make up continuity, which is difficult for us to draw an exact boundary between them.

Subjectively, the frequent use of hedges looks redundant in the female award speech. On the perspective of cooperative principle, maybe hedges go against its quality and quantity principle. In fact, it is the strict observance of cooperative principle, reflecting female winner’s inner thoughts, their emotional inspiration and cognition. From the qualitative point of view, so many plausibility shields the speecher uses to express feelings may reduce the reliability of the information. From the quantitative point of view, the use of hedges when talking about personal thoughts and feelings, emotions and life topics, may provide too much or too little information available that needs selecting. However, hedges do not violate the principles of cooperation, but supply the greatest amount of information making communication more precise so that the subjective language is closer to objective facts.

（7）“I know they’re in here and you’ll probably hear her in a minute. Maybe not.”-- Sandra Bullock

The plausibility shields , “I know”, “probably” and “maybe” do not change the original meaning of the discourse structure, just adding a note to make sure that the original tone tends to be ease. On the whole, it is really easing the speaker’s tone. The speaker uses the word “maybe” for the overall information because she is unsure whether her families are here or not. Whatever, it gives an opportunity for speakers’ further action.

（8）“I’d be lying if I have not made a version of this speech before, I think I was probably 8 years old and staring into the bathroom mirror.”-- Kate Winslet

“I think” and “probably” are used to show the winner can’t remember the exact age of her obscure memory. The advantage of the two plausibility shields is to avoid mistakes, confirm to quality and quantity principle and reflect the objective facts.

Same with both of the parties in the contradictory transferring with each other under certain conditions, language, whether scientific language or daily language, have both accurate expressions and vague concepts. This contradiction could transfer into the opposite under certain conditions, which means the vague surface is to make the session more accurate in reality.

5.2 Showing courtesy

Courtesy is the basic requirement of interpersonal communication. To keep good interpersonal relationships is closely related to courtesy. As Leech’s politeness principle explains, taking politeness into consideration, the speaker would violate the principles of cooperation to achieve expressing one’s true thoughts implicitly effect. From the perspective of politeness, women’s using the high frequency of hedges has become a common verbal communication strategy. Zhang Xiaohui (2009) thought that hedges were widely used in the female utterance. That weakens the speaker’s tone to a certain extent, which looks more polite and more easily accepted by the listener in order to maintain a harmonious, good communication relationship. As all the speakers are the public figures in the film entertainment, the more the public require speakers’ image, the higher the degree of politeness reaches. The winners will use hedges frequently in the respect of politeness principle so as to show courtesy in public to a greater degree. As a result, under the circumstance of expressing clearly, trying to avoid imposing their views on others and arbitrary helps improve the appropriateness and acceptability of discourse, thereby enhancing the strength and validity of persuasion as well as avoiding losing others’ face.

Brown and Levinson proposed the saving-face theory. The so-called “face” is actually “personal image”. Every member of society are urgent to earn for their own desire in public. It can be divided into the positive face and negative face. To be polite is to relieve threat of some communication. All in all, the use of hedges can make the speaker seem more polite, modest and dignified. Due to the particularity of speakers’ identity and the spread of communication, it’s necessary for them to blur their attitude or view in the enhancement of the acceptability and politeness of discourse.

（9）“Gabby, I love you so much. You are exquisite. You are beyond words to me.”-- Sandra Bullock

（10）“Helen, I feel like we are family through family and I don’t have the words to express just what I think of you.”-- Sandra Bullock

In the two sentences above, winners use a series of hedges “so much”, “beyond words”, “I feel like”, “just” and “I think of”, when they refer to the competitors. In compliance with generosity maxim and approbation maxim, it fully embodies women appreciation of opponents in avoidance of hurting others’ face.

5.3 Self-protection and Self-presenting

It is quite easy for women to run into awkward situation when talking about life, emotion and kind of sensitive topics. At this point, the proper use of hedges can help them express themselves better to get the point of self-protection. It’s certain that hedges are playing an increasingly important part in protecting people’s reputation. All the speakers are aimed at expressing their views and attitudes, or defining their position. As a fuzzy strategy, the application of hedges makes it possible to avoid being absolute and extreme. Consequently, it is believed that hedges do subtly cover up some aspect of ignorance and lack of knowledge.

In consideration of women’s vulnerable mental factor and low social status, women are more likely to use hedges to express their views. It’s able to obtain effects of saving face, self-protection, showing self-value, establishment of politeness, gentleness and pretty image as well as wining others’ recognition and appreciation.

（11）“There was no division between the cast and the crew on this film, and that’s what made it so special”-- Kate Winslet

The usage of “between the cast and the crew” and “so” put emphasis on the film attributing the success to all the staff of the team, not merely the actors. It shows the speaker’s charming and self-value.

（12）“I, in particular, failed to thank one.”-- Sandra Bullock

“In particular” stresses her personal efforts for their own self-presenting getting an opportunity to let more people know and understand speaker.

As a public figure on the screen, it is of great importance to protect and present them. Therefore, the effective use of hedges in their communication can be perfect show of personal charm to shape the image of the fans better, which will help publicity.

6 Conclusion

As a part of the fuzzy language family, hedges are the most common, typical, and of most worthy researching in all of the language phenomena. The author hopes to have shown the distinct importance and revealed the female characteristic on hedges. Based on the analysis and discussion of women’s speech on the award ceremonies in the film and television circle, the conclusion can be drawn that hedges has been a characteristic in female utterance. Affected by plenty of factors in daily life, women have to make full use of hedges in order to achieve precise speech, courtesy, humility and self-protection. Therefore, the effective use of hedges has become the usual means of communication and expressing for women.

Bibliography

Channell, Joanna. Vague Language[M]. Shanghai: Shanghai Foreign Language

Education Press, 2001. Crystal, Da.

董娜. 模糊限制语的界定及分类[J]. 北京第二外国语学院学报, 2003(4): 28-34

李福印, 陈林华. 交际中的模糊限制语[J]. 外国语, 1994(5): 55-59

黎千驹. 《模糊语义学导论》[M]. 北京: 社会科学文献出版社, 2007

亢娟妮. 模糊限制语在英语广播新闻报道中的功能[J]. 高等教育与学术研究, 2009(3): 90-93

水淼. 模糊限制语·语用功能·女性[J]. 语文学刊, 2008(1): 80-83

王晓红. 模糊限制语在言语学位论文中使用情况的调查分析[J]. 鸡西大学学报, 2009(6): 92-93

王鹏, 孙斐然. 女性语言中模糊限制语的语用功能探析[J]. 枣庄学院学报,

2009(3): 38-40

魏晓芳. 新闻语篇中的模糊限制语[J]. 成都大学学报（社科版）, 2010(1): 45-47

伍铁平. 模糊语言学综论[J]. 西南师范大学学报, 1997(8): 88-90

姚克勤. 英语政治新闻中模糊限制语的词汇特征及其应用[J]. 技术与创新管理, 2010(2): 244-246

杨平. 英汉范围变动型模糊限制语对比研究[J]. 解放军外国语学院学报,

2001(4): 13-17

于强福. 明清四大名着中模糊限制语的翻译策略探讨[J]. 外语教育,

2009: 182-186

张晓慧. 模糊限制语视角下的女性话语特征分析[J]. 商丘师范学院学报,

2009(10): 120-122

曾文雄. 模糊限制语的语言学研究回顾与发展[J]. 社科纵横, 2005(2): 153-155

曾文雄. 模糊限制语的语言学理论与应用研究[J]. 外语教学, 2005(4): 27-30

周娟. 从跨文化交际角度谈英语模糊限制语在经济文体中的体现[J]. 孙阳师范高等专科学校学报, 2010(1): 133-136

周红. 英汉变动型模糊限制语及其语用功能[J]. 外语研究, 2008(2): 40-44

赵蓉晖. 《语言与性别》[M]. 上海: 上海外语教育出版社, 2003

Acknowledgements

First, I want to give special thanks to my supervisor, Professor Zhou Hong, for checking the manuscript and providing numerous helpful comments and suggestions.

I am also very grateful to other professors who offered their rare advice during my classes.

Finally, the completion of my thesis could not have been possible without the constant support and encouragements from my roommate and classmates. I want to express my special gratitude to them all.

本文来源：https://www.2haoxitong.net/k/doc/95b58ccc0e22590102020740be1e650e52eacf95.html