【英语论文】英语中的歧义现象An Analysis on Ambiguity in English_英语歧义现象分析
【英语论文】英语中的歧义现象An Analysis on Ambiguity in English由刀豆文库小编整理,希望给你工作、学习、生活带来方便,猜你可能喜欢“英语歧义现象分析”。
毕业设计(论文)
毕业论文题目:
毕业论文
An Analysis on Ambiguity in English1
毕业设计(论文)
Abstract
Ambiguity is omnipresent in languages.There have been a lot of researches about ambiguity in the past.This paper makes a comprehensive analysis on the ambiguous structures in English and claifies categories of them based on the different causes: phonological ambiguity, lexical ambiguity, structural(grammatical)ambiguity and pragmatic ambiguity.The phenomenon of ambiguity, whenever and wherever it occurs, may directly lead to the comprehension of expreion and communication.Phonetic ambiguity, that is, a word or a phrase sounds which has at least two meanings, which occurs only in spoken English but not in written English.Lexical ambiguity might cause much more complicated problems in the understanding of the language, for it exists not only in spoken form but also in written language.Its existence is attributed to certain ambiguous lexical items, namely to polysemous and homonymous words.In written language, the most important ambiguity phenomenon lies in structure.Structural ambiguity is also called grammatical ambiguity, which means “ambiguity caused by the varied interrelationships between words in a sentence.Even though none word is ambiguous, structurally it still generates ambiguity”.Structural ambiguity is often caused by the linear order of words in a sentence.It often takes place in spoken languages as well as in common phonetic materials.Pragmatic ambiguity denotes that the language exprees different purposes or meanings in the real application.Ambiguity analysis can help improve the ability in language understanding and language application.Key Words: phonological ambiguity, lexical ambiguity, structural ambiguity, pragmatic ambiguity
毕业设计(论文)
摘要
歧义现象在语言中无所不在,在过去已有许多相关的研究。这篇论文将对英语中所存在的歧义现象做一个全面的分析。根据不同的原因,英语歧义现象总体来说可分为四大类:语音歧义,词汇歧义,结构歧义(语法歧义)和语用歧义。不论在任何时间任何地点出现歧义现象,都会对人们的理解和交流造成很大的困难。语音歧义是说一个单词或一个词组听起来至少有两个意思,这种现象只会出现在口语中。词汇歧义是指由于一词多意或同形异义的原因给人们的理解造成了许多困难。这种现象可存在于口语和书面语中。在书面语中,最重要的歧义是结构歧义,也叫语法歧义,它是由词与词之间不同的关系所造成的。即使一个句子中所有的单词都没有歧义,句子的结构也会造成歧义。语用歧义是指说话人在特定的语境中或上下文中使用不确定的或模糊的或间接的话语向听话人同时表达数种言外行为或言外之意。
关键词:语音歧义,词汇歧义,结构歧义,语用歧义
毕业设计(论文)
Contents Introduction………… ……………………………………………………6 1.1 Definition of Ambiguity in English....................................................................6 1.2 Importance of the Present Study……………………………………………….6Phonetic Ambiguity……………………………………………………….6 2.1 Phonetic ambiguity caused by homophones……………………………………7 2.2 Phonetic ambiguity caused by phrases…………………………………………7 2.3 Phonetic ambiguity caused by different breath groups and different intonation.7 2.4 Phonetic ambiguity caused by stre…………………………………………...7 Lexical Ambiguity………………………………………………………...8
3.1 Lexical Ambiguity caused by homonym………………………………………8 3.2 Lexical Ambiguity caused by polysemy……………………………………….9Structural ambiguity…………………………………………………….10
4.1 Sententially structural ambiguity…………………………………………......10 4.2 Phrasally structural ambiguity………………………………………………...12Pragmatic ambiguity…………………………………………………….13
毕业设计(论文)
5.1 Pragmatic ambiguity caused by implication……………………………13 5.2 Pragmatic ambiguity caused by transcultural background………………..14Conclusion………………………………………………………….15
毕业设计(论文)Introduction
1.1 Definition of Ambiguity in English Ambiguity, as is defined in the Webster‟s Third International Dictionary(许素波,Types of Ambiguity in English,1999-04), is “the condition of admitting of two or more meanings, of being understood in more than one way, or of referring to two or more things at the same time.” In ordinary books on linguistics, it is generally defined roughly as linguistic phenomenon that a word phrase or clause can have more than one interpretation.Ambiguity, as a pervasive feature of the English language, existing in both spoken and written forms, and occurs for a variety of reasons, such as the phonetic reason that in connected speech, two or more different strings of lexical items happen to take on the same phonological form as a result of sound liaison, the lexical reason, for instance, ambiguity can be given rise to owing to the homonymy and polysemy of the vocabulary, and the structural reason, namely ambiguity can also be attributed to different grammatical analysis of a phrase or clause.Ambiguity can exist in both spoken and written forms of English and arise through a variety of ways.From a purely linguistic point of view, however, ambiguity can be accounted for by mainly four factors: the phonetic, the lexical, the structural, and the pragmatic, hence four types of ambiguity occur: phonetic ambiguity, lexical ambiguity, structural ambiguity, and pragmatic ambiguity.1.2 Importance of the Present Study Through the present study of ambiguity, we can avoid misunderstanding caused by ambiguity effectively.Meanwhile, this can also help the learners improve their understanding and translation of English.Besides, by doing so, language users can get the effect of rhetorical speech of pun in order to enrich the language and make the language more humorous.What‟s more, the study of ambiguity in English may also help to confirm some universal features of language and university of people‟s thinking and may reveal some cultural differences.In short, the present study of ambiguity in English can arouse many people‟s interest and will help people to attain a better understanding of how language works in people‟s mind.During our time of learning English, we should attach more importance to it.Phonetic Ambiguity
Phonetic ambiguity, that is, a word or a phrase sounds that it has at least two meanings, occurs only in spoken English but not in written English(邱述德 英语歧义 1998).6
毕业设计(论文)
2.1 Phonetic ambiguity caused by homophones Homophone means that a word that is pronounced like another word but has a different spelling or meaning(张韵斐 现代英语词汇学概论 2004).The examples analyzed below are several pairs of words which have the same sound but different meanings.If they appear in the spoken language, you will have difficulty in telling them apart.(1)a: He is sowing now.b: He is sewing now.sow and sew have the same pronunciation, however, sow in sentence a means “to plant or scatter seeds”, and sew in sentence b means “to join pieces of cloth together using a needle and thread”.(2)a: Throw the flower away.b: Throw the flower away.flower and flour are a pair of homophones, flower: noun, the part of a plant, often beautiful and colored, that produces seeds or fruit, flour: noun, power made from wheat and used for making bread or cakes.In spoken language, it is difficult for you to tell flower and flour apart.(3)a: He is flying to Oakland.b: He is flying to Oakland.Oakland in sentence a is a city of State California, but Oakland in sentence b is a city of New Zealand.They are a pair of homophones.(4)“When does the baker follow his trade?” “Whenever he kneads the dough.”
This example uses “need” and “ knead” which are a pair of homophones and added the polysemous word” dough”(In slang, this word means money),which makes it difficult for us to know that whether the baker begins his busine when he needs the money or the baker begins his busine when he rubs the dough.2.2 Phonetic ambiguity caused by phrases Phrases that are formed of more than one word usually contain the following elements: head, specifier and complement(The word around which a phrase is formed is termed head.The word on the left side of the heads are said to function as specifier.The words on the right side of the heads are complement)(戴炜栋 简明英语语言学教程 1989).If the end of one word is a consonant sound while the next begins with a vowel, the consonant sounds naturally to be the part of the next word.This phonetic rule, as everybody knows, is called sound-linking or sound liaison.This phenomenon as often as not cause ambiguity, for example, a bee feeder / a beef eater
毕业设计(论文)
The two phrases sound similarly, however, the meaning of the former is absolutely different from the latter.The former means that a man who feeds bee, while the latter means that a man who eats beef.There are a lot of similar examples: a trained deer/ a train dear;a name / an aim;a nice girl / an ice girl;an ear-phone / a near phone.2.3 Phonetic ambiguity caused by different breath groups and different intonation(1)A range of sounds of some words which constitute a sentence pronounce together without stop called breath group(邱述德 英语歧义 1998).“Peter is a short story writer”
This sentence has two meanings because of different breath groups.One is that Peter is a story writer who is short(Peter is / a short / story writer), the other is that Peter is a writer who is good at writing short stories(Peter is / a short story / writer).(2)The rise and the fall of the voice in speaking, especially as this affects the meaning of what is said called intonation.“I beg your pardon”.If this sentence is said with a rising tone, it means “please say it again”.If it is said with a falling tone, it means “I am sorry, please forgive me”.2.4 Phonetic ambiguity caused by stre Stre means that a term used in semantic analysis to refer to a lexical item which has a range of different meanings(戴炜栋 简明英语语言学教程 1989).The peasant grows a lot of fruit.They eat what they can, and can what they cannot.In this sentence, when the verb “can” is streed, it means “to preserve food by putting it in a can”, the sentence means they eat the food which is putted in a can.When it is unstreed, it means “be able to”, used as a modal verb, the sentence means they eat what they are be able to eat the amount of the food.Phonetic ambiguity sometimes does cause misunderstanding to people, yet it could be got rid of if enough attention is paid to the context in which the utterance concerned is made, and to the phonetic features of the language in speech.Lexical Ambiguity
Compared with the phonetic ambiguity, lexical ambiguity might cause much more complicated problems in the understanding of the language, for it exists not only in spoken form but also in written language.Its existence is attributed to certain ambiguous lexical items, namely to polysemous and homonymous words which bound in the English vocabulary.毕业设计(论文)
3.1 Lexical Ambiguity caused by homonym In the English, there are many pairs of groups of words, which, though different in meaning, are pronounced alike, or spelled alike, or both, such words are called homonyms(张韵斐 现代英语词汇学概论 2004).(1)He took the lead yesterday.This is a very simple sentence both lexically and structurally, but it is ambiguous.Here the ambiguity resides in the homographic word “lead”.Pronounced either as [li:d],meaning “a leading role or part” or as [led] meaning “a kind of metal”.Thus the sentence may be interpreted to mean either that “He took a leading part(in a certain activity)yesterday” or that “He took away the lead(a kind of metal)yesterday”.(2)After operation, he could not bear children.Here the perfect homonym “bear” must necearily function syntactically as a verb, but the sentence itself can not tell which of the meanings was intended by the speaker or writer.Does it mean “give birth to;produce” or “put up with;tolerate”? In this case, the context in which the sentence is uttered or used often serves to remove the potential ambiguity.(3)He likes China(china).In this sentence, “China” and “china” may be said to be a pair of homophonic words.“China” with the first letter capitalized, denotes “a country in Asia”, while “china” with the first letter in its small form, means “crockery”.It is neceary to say that this kind of ambiguity caused by homophones, only exists in spoken English.Spell out, and the homophonic word will become disambiguated immediately.3.2 Lexical Ambiguity caused by polysemy A term used in semantic analysis to refer to a lexical item which has a range of different meanings(张韵斐 现代英语词汇学概论 2004).(1)The food is not hot.The word “hot” can be translated into “having a high temperature” or “spicy”.(2)He refused to pay for the board.Here ambiguity obtains on account of the polysemous word “board”.The sentence can either be interpreted as “He refused to give money for his meals” or as “He refuses to pay money for the councilors” or even as “He refuses to pay money for the “table”, etc.in the absence of the context.(3)She is an English teacher.This nominal phrase “an English teacher” can be comprehended in “a teacher from England” or “a teacher who teaches English language”.From the above for examples, a conclusion may be drawn that some sentences obtain ambiguity in both written and spoken form, while some, which are ambiguous in written form,毕业设计(论文)
may be free from the ambiguity in speech or vice verse.It is a fact that most ambiguous sentences of this kind will become disambiguated when provided with the context, but in not few cases they may cause confusion, uncertainty and misunderstanding in the mind of the listener or reader.It is also arranged on the part of literary men for stylistic purpose to achieve a variety of stylistic effects such as humor, irony, emphasis and contrast, etc.For example, a very commonly-used and effective rhetorical device, are the results of making use of polysemous and homonymous words purposely so as to make the sentences ambiguous.Structural ambiguity
In written language materials, the most important ambiguity phenomenon lies in structure.Structural ambiguity is also called grammatical ambiguity, which means “ambiguity caused by the varied interrelationships between words in a sentence.Even though none word is ambiguous, structurally it might still generate ambiguity”(何冬兰 On English Structural Ambiguity 2006-06).Structural ambiguity is often caused by the linear order of words in a sentence.It often takes place in spoken languages as well as in common phonetic materials.Structural ambiguity can be divided into two types, one is sententially structural ambiguity;the other is phrasally structural ambiguity.4.1 Sentential structural ambiguity
This kind of ambiguity only exists within a certain kinds of sentences, which are specially structured.Unlike phrasal structural ambiguity, it could not be discued without the context of sentences.4.1.1 Caused by the simplified forms of comparative structure In English, adverbial clause of comparative degree is often abridged.It is easy to cause ambiguity.We can sort it out and analyze it.Example 1: I know him better than you.It can be explained as “I know him better than you do” or as “I know him better than I know you.”
Example 2: Lily likes Harry as well as Joe.It can be understood as “Lily likes Harry as well as Joe does” or as “Lily likes Harry as well as she likes Joe”.4.1.2 Caused by negative word “not”
In a sentence, if the predicate is negative, and being attached by an adverbial modifier, it might generate ambiguity.Example 1: Jeica didn‟t prepare her leons well yesterday.毕业设计(论文)
This sentence could be explained as three structures:(1)Yesterday, Jeica didn‟t prepare her leons well.(She did something else.)(2)Yesterday, Jeica prepared her leons, but not well enough.(3)Jeica prepared her leons well, but not in yesterday.Example 2: He didn‟t go because he was afraid.And this sentence has two different structures:(1)He was afraid, so he didn‟t go.(2)He went, but not because he was afraid.In this sentence pattern, the negative word “not” in the main clause could either negate the main clause or the subordinate clause.Hence ambiguity takes place.4.1.3 Caused by adverbial or adverbial clause Example: Go straight forward and then turn left when you see a children‟s cinema.”
“When” introduces a time adverbial clause.It can modify “then turn left”, meaning “Go straight forward, you will see a children‟s cinema, and then turn left.” It can also modify the whole sentence, meaning “When you see a children‟s cinema, go straight forward and then turn left.”
4.1.4 Caused by fixed sentence patterns Example 1: It is good for him to do so.In this sentence pattern, ambiguity is caused by “for him”.It has two widely divergent meaning.(1)He is so kind that he does so.(2)What he does is good for him.Example 2: Eric is too good a man to kill.The verb after a verbal infinitive could be either active form or paive form.So the subject of the sentence could both be agent or victim.The two structures are:(1)Eric is too good a man for him to kill others.(2)Eric is too good a man for others to kill him.4.1.5 Caused by the simplified forms of parataxis Similar to the simplified forms of comparative structure, in a simplified form of parataxis, the latter compound clause is abridged, leaving only one or two constituents, which might be relevant to the subject or the object(or the object clause)in the front clause.Example 1: Lucy gave Monica a nickel and Mary a dime.Here “Mary a dime” is an ambiguous item.“Mary” could have the position as “Lucy”.Then it is the subject of the latter clause while the indirect object “Monica” is left out.Or it could have the position as “Monica”.Then it is the indirect object of the latter clause while the subject “Lucy” is left out.So the full structures for the two divergent meaning are:(1)Lucy gave Monica a nickel and Mary gave Monica a dime.(2)Lucy gave Monica a nickel and gave Mary a dime.毕业设计(论文)
The use of auxiliary verb is also one factor of causing such kind of ambiguity.Please look at the following example.Example 2: John thought Ivan went to Japan and Phillip did too.“Did” here would refer to either “thought” or “went”.And the two poible structures are:(1)John thought Ivan went to Japan and Phillip also thought Ivan went to Japan.(2)John thought Ivan went to Japan and he thought Phillip went to Japan too.4.1.6 Caused by some word’s special syntactic function
Some words in English, mainly conjunctions, adverbs and pronouns that introduce subordinate clause, have more than one syntactic function.Example: Go and ask the teacher by the window who is going to give you leons in art.In this sentence, ambiguity is triggered by “ask”, which could be attached to with only a direct object, only an indirect object, or both of them.So the sentence could be explained as:(1)Go and ask the teacher by the window.He is going to give you leons in art..(2)Go and ask the teacher by the window.He might know who is going to give you leons in art.4.2 Phrasally structural ambiguity
It‟s common to find one central word with two or more than two modifiers.When being lack of limit of the choice or contextual clues, the relationship between the modifiers and the central word might be ambiguous.English grammar is flexible and changeable.So does the word‟s collocation.Hence the existence of structural ambiguity is inevitable.4.2.1 Caused by Shift of Parts of Speech Shifts of parts of speech have several situations, but basically because of the uncertainty of the word‟s part of speech.For example, “can fish”.This phrase might mean “be able to fish”.Or “put the fish into a can”.The cause of ambiguity in this sentence is the part of speech of the word “can”, which has two circumstances.“can” might be a model verb or a transitive verb.At the same time, the word “fish” might be an intransitive verb or a noun.This is only one common example;I would like to sum up the examples into certain ambiguous forms as following.a).N/V + V/N Example: ship sails It‟s hard to decide the part of speech of either “ship” or “sails”.There are two poibilities: “ship sails(N + V)” or “ship sails(V + N)”.The first structure means “a ship will sail”.And the second structure means “someone will ship the sails”.This kind of ambiguity item can be easily found in telegrams or newspapers.b).Adj./N + N Example: a Chinese teacher This phrase has two structures: “a Chinese teacher(Adj.+ N)” or “a Chinese teacher(N + N)”.The first structure means “a teacher who is Chinese”.And the second structure means “a teacher
毕业设计(论文)
who teaches Chinese”.c).“V + N + V” or “V + Adj./ Pron./ Poeion + N” Example: make her dre fast This phrase has two structures: “make her dre fast(V + N + V)” or “make her dre fast(V +Adj./ Pron./ Poeion +N)”.The first structure means “tell her to dre herself quickly”.And the second structure means “have her dre made quickly”.4.2.2 Caused by Constituent Structure or Phrase Structure a).Adj.+ N + Conj.+ N
Example: ugly frog and tortoise
The poible structures are “(ugly frog)and tortoise” or “ugly(frog and tortoise)”.b).Adj.+ N‟s + N
Example: a nice boy‟s car
The poible structures are “(a nice boy)‟s car” or “a nice(boy‟s car)”.c).Adj.+ N + N Example: foreign language teacher The poible structures are “(foreign language)teacher” or “foreign(language teacher)”.d).N1 and N2 or N3 Example: John and Sam or Tom The poible structures are “(John and Sam)or Tom” or „‟John and(Sam or Tom)”.e).V + N1 + Prep.+ N2 Example: see a boy with a telescope The ambiguous item is the PP attachment “with a telescope”.It can attach to “see” or “a boy”.In the first case, it means “use a telescope to see a boy”.And the latter case means “see a boy who has a telescope”.f).N1 of N2
Example: the love of God This phrase has two meanings: “someone‟s love to God” or “God‟s love to someone”.g).N + N + N +… Example1: girl hunter
This phrase is rather special for structural ambiguity.It has only one structure, but it has two poible meanings because it is not easy to decide the role of “girl”.This phrase might mean “a girl who is a hunter” or “a hunter who hunts girl”.This is not lexical ambiguity, but a kind of receive structural ambiguity caused by the special function of certain phrase structure.Pragmatic ambiguity
Pragmatic ambiguity denotes that the language exprees different purpose or meaning in the
毕业设计(论文)
real application(邱述德 英语歧义 1998).Quite a few people like using ambiguous and indirect sentences to describe connotation deliberately.5.1 Pragmatic ambiguity caused by implication(1)A: What do you want to do this afternoon? B: I have a terrible backache.The answer of B is to expre the fact that he has a terrible backache.However, as a matter of fact, his intention is that he wants to let A know he will not do anything at all this afternoon.(2)A: Synden is the capital of Australia, isn‟t it, teacher? B: And New York is China, I suppose.The answer of B is out of aociation of with the question of A.But in fact this way is “the wrong answer versus the wrong sentence” to describe the conclusion of A is very absurd.5.2 Pragmatic ambiguity caused by transcultural background(1)The Englishmen translate “a flat tyre” into “a tyre without enough air inside” while the Americans into “a very foolish man”.Another example we may use to illustrate this point goes like this: A British girl toured around America and guided by an American girl.They conversed with each other after a whole day of tour.Br: Let me have a rest.I am already knocked up.Am: My heartiest congratulation!Br: Why do you say that? Am: Why shouldn‟t I?
The phrase “knock up” means “pregnant” in America, but “very tired” in Britain.So, the British girl is baffled when she hears the American girl‟s “My heartiest congratulation”.(2)A: Do people often die in this village?
B: No, they only die once.A: Do a lot of people die in this village?
B: Yes, all of them do.“people often die” can be understood into “the matter which people die often happen” or “people die more than one time”, and “ a lot of people die” into “many people die” or “the matter which people die often happen”.B makes an “honest” comprehension of A‟s remarks, which result from the difference between subjective culture and objective one.(3)Once there was a factory in which “horizontal store refrigerator” were produced.On the model-label of refrigerators, “W.C”---the abbreviation of the Chinese phonetic alphabet of “卧藏”.“W.C” is just the same as the abbreviation of the word “water-closet” in English.This caused too much misunderstanding.To sum up, pragmatic ambiguity is a phenomenon that cannot be avoided in the use of language.It can cause misunderstanding and even anger between the people.Therefore, in the
毕业设计(论文)
conversation, we should listen carefully to know the speaker‟s intention.Besides, when we talk with a foreigner, we should understand the culture of his country before.However, if pragmatic ambiguity used properly, we can enhance the effect of expreion.Conclusion
So far, the four basic types of ambiguity, the phonetic, lexical, structural and pragmatic, have been discued and dealt with separately;but it should be pointed out that in authentic language, they do not always appear separately, instead they might mingle together and reside in one sentence at the same time.This really requires much attention.From all the analyses made in this thesis, a fact shows itself that apart from the linguistic reasons, i.e.the phonetic, lexical structural and pragmatic ones that bring about ambiguity, another important factor which, to a great extent, is responsible for the lack of context.Most of the examples cited in the thesis will become disambiguated when they are placed in the context in which they are used, because context dependence is a universal feature of human languages.Context plays a vital role in the determination of word meaning and sentence meaning.Based on this fact, it necearily follows that a succeful communication requires not only a sufficient knowledge in linguistics, say, phonetics, lexicology, syntax and pragmatics which makes it poible to recognize the four major types of ambiguity that may arise at any time in using the language, but also that close attention should be paid to the context, which can serve as the only available means to remove the potential ambiguities.In short, to cope with the subtle language, one should not only be armed with sufficient knowledge in linguistics, but also should be attentive and observant enough to the context, the most important factor which plays a vital role ill the determination of word meaning or sentence meaning.The knowledge in linguistics can help to recognize potential ambiguities while a keen awarene of the context can help to remove them.The combination of the two is sure to lead to a good understanding and a rich appreciation of the language.毕业设计(论文)
References
1. 戴炜栋
简明英语语言学教程
上海外语教育出版社
1989 2. 邱述德
英语歧义
商务印书馆
1998 3. 赵元任 汉语中的歧义现象[A].吴宗济,赵新那.赵元任语言学论文集[C].北京:商务印书馆,2002 4.孙英华.英语结构歧义现象的分析[A].李光立,何福胜.研究生英语教学研究论文集[C].北京:中国人民大学出版社,1998 5.程工.从对歧义句的分析看20世纪的句法学[J].解放军外语学院学报.1998 6.冯志伟.论奇异结构的潜在性[Z].Internet.8 May, 2004.Available: http://162.105.203.93/research/papers/chinese/collection-2/ambig2.htm 7.Liliance Haegeman and Jacqueline Gueron.The New Comparative Syntax [A].In Reading of Linguistic[C].eds.杨达复,谭志明.西北工业大学出版社,2003.201~208 8.陈思敏.试用X-标阶理论来消解歧义[J].外语与外语教学.1999,(3).53~55 9.秦洪林、贾德霖.英语歧义研究,江苏教育出版社 1991年 10.伍谦光.语义学导论,湖南教育出版 1987年 11.沈家煊.英语中歧义类型,《现代外语》, 1985年第1期
毕业设计(论文)
Acknowledgement
My deep gratitude first goes to Wang Huamin, my supervisor, who has given me a lot of enlightening instructions and guided me through the various stages of writing this thesis.Without his guidance and valuable suggestions, the completion of the present thesis would not have been poible.Besides, her learnedne, kindne and readine to help students are well acclaimed among all the students.Special thanks also go to Profeor Jiang Xiping, from whose illuminating lectures I have benefited a lot.She has kindly provided me with the materials I need, taken pains to read my papers and given me some valuable advice.I really appreciate her unreserved help and will keep it in my mind for ever.Sincere thanks goes as well to Profeor Liu Shifa whose profundity, eloquence and integrity have made a strong impreion on me and whose care and encouragement are of great importance to me.Besides, I would like to thank all the other teachers for their great lectures and all the students who have given me a lot of help and have made the completion of this thesis poible and made my study in university easier, more convenient and more enjoyable for me.Finally, I want to thank my family for their everlasting understanding and support to my study.