A study on teachers’use of vietnamese in english lessons at an duong high school, hai phong

54 22 0
A study on teachers’use of vietnamese in english lessons at an duong high school, hai phong

Đang tải... (xem toàn văn)

Tài liệu hạn chế xem trước, để xem đầy đủ mời bạn chọn Tải xuống

Thông tin tài liệu

VIETNAM NATIONAL UNIVERSITY- HANOI UNIVERSITY OF LANGUAGES AND INTERNATIONAL STUDIES FALCUTY OF POST-GRADUATE STUDIES -****** NGUYỄN THỊ SINH A STUDY ON TEACHERS’ USE OF VIETNAMESE IN ENGLISH LESSONS AT AN DUONG HIGH SCHOOL, HAI PHONG Nghiên cứu việc sử dụng tiếng Việt giáo viên dạy tiếng Anh trường THPT An Dương, Hải Phòng M.A MINOR PROGRAMME THESIS Field : English teaching methodology Code : 60.14.10 Ha noi - 2012 VIETNAM NATIONAL UNIVERSITY- HANOI UNIVERSITY OF LANGUAGES AND INTERNATIONAL STUDIES FALCUTY OF POST-GRADUATE STUDIES -****** NGUYỄN THỊ SINH A STUDY ON TEACHERS’ USE OF VIETNAMESE IN ENGLISH LESSONS AT AN DUONG HIGH SCHOOL, HAI PHONG Nghiên cứu việc sử dụng tiếng Việt giáo viên dạy tiếng Anh trường THPT An Dương, Hải Phòng M.A MINOR PROGRAMME THESIS Field : English teaching methodology Code : 60.14.10 Supervisor : Dr LÊ VĂN CANH Ha noi - 2012 TABLE OF CONTENTS ACKOWLEDGEMENTS……………………………………………………………… …i ABSTRACT……………………………………………………………………………… ii TABLE OF CONTENT………………………………………………………………… …iii LIST OF ABBREVIATIONS……………………………………………………………… vi LIST OF TABLES ………………………………………………………… …………… vii PART A- INTRODUCTION…………………………………………………………… 1 Background to the study………………………………………………………… …1 The aim of the study…………………………………………………………… ….2 Research questions………………………………………………………………… Scope of the study………………………………………………………………… The significance of the study……………………………………………………… Design of the study……………………………………………………………….…3 PART B DEVELOPMENT…………………………………………………….……… CHAPTER LITERATURE REVIEW……………………………………………… History of language teaching methods focusing on L1 use in L2 teaching………………………………………………………………………………… Debate surrounding the role of L1 in the L2 classroom……………………… ….6 2.1 Support for the monolingual approach………………………………… …6 2.2 Support for the bilingual approach……………………………………………… Studies exploring L1 use in L2 teaching………………………………… ……… 3.1 Studies aiming at demonstrating the positive role of L1 in L2 teaching……… 10 3.2 Studies focusing on teachers and learners‘ attitudes toward L1 use in L2 teaching and specific situations in which L1 should be used in the L2 classroom…………………………………………………………………………… .11 Conclusion……………………………………………………… ………………….13 CHAPTER THE STUDY……………………………………………………………… 14 2.1 Introduction………………………………………………… …………… …….14 2.2 Situation analysis……………………………………………………… ……… 14 2.2.1 The setting of the study……………………………………………………….14 2.2.2 Teachers…………………………………………………………………… 15 2.2.3 Students…………………………………………………………………… 16 2.2.4 Teaching and learning materials…………………………….…………… 16 2.3 Participants……………………………………………………………… ……… 18 2.4 Data collection instruments…………………………………………… ………….18 2.4.1 Survey questionnaires…………………………………………………….….18 2.4.1.1 Questionnaire for students……………………………………………… 19 2.4.1.2 Quetionnaire for teachers……………………………….……………… 19 2.4.2 Interviews…………………………………………….…………………… 20 i 2.4.3 Class obsevations………………………………………………………… 20 2.5 The detailed results of the survey…………………………………………… … 20 2.5.1 Teachers‘ frequency of L1 use……………………………………………… 21 2.5.2 Teachers‘purposes of L1 use………………………………………………… 21 2.5.3 Results of the questionnaires on the use of Vietnamese in the English classroom ……………………………………………………………………………………… 23 2.5.4 Interview s…………………………………………………………………… 29 2.6 Conclusion…………………………………………………………… ………… 31 CHAPTER CONCLUSION………………………… 32 3.1 Major findings………………………………………………………………….32 3.2 Implications…………………………………………………………………….34 PART C CONCLUSION…………………………………………………………………36 Summary of the study……………………………………………………… ….36 Limitations……………………………………………………………………….36 Suggestions for further research…………………………………………… ….36 REFERENCES……………………………………………………………………… 38 APPENDICES………………………………………………………………………….41 Appendix Questionnaire for teachers…………………………………………………41 Appendix Questionnaire for students…………………………………………………43 Appendix Interview questions…………………………………………………… 47 ii LIST OF ABBREVIATIONS CLT : Communicative Language Teaching ELT : English Language Teaching L1 : First language L2 : Second language iii LIST OF TABLES Table 1: Teachers’ frequency of using Vietnamese in the lessons………………… …20 Table Teachers’ purposes of using Vietnamese in the observed English lessons ….21 Table Teachers’ purposes of using Vietnamese according to the questionnaire responses………………………………………………………………………………………… 23 Table Frequency of teachers’ use of Vietnamese as reported by the students……… 25 Table Students’ attitudes to the purposes of teachers’ use of Vietnamese……….… 25 Table Teachers’ and Students’ attitudes to the purpose of using Vietnamese……… 27 iv PART A INTRODUCTION As the starting point of the study, this introductory chapter provides the background to the study and identifies the problem that the thesis attempts to solve, states the aim and the significance of the study, as well as research question, and provides an outline of the thesis Background to the study Learning a foreign language is found useful in all areas in the modern society English becomes the main language among many languages that people want to learn That is the reason why English is the foreign language which is being taught in most schools or Centers in Vietnam This, in turn, generates a must to equip learners with a good method of learning and teachers should apply appropriate methods to present lessons to the learners in order to get the best results Several studies conducted with the aim of improving the quality of teaching and learning English in Vietnam show that ―traditional pedagogy, emphasizing the acquisition of grammar and vocabulary rather than communicative competence‖ (Pham, 2005, p 2) is one of the causes of the problem Since the early 1990s, therefore, Communicative Language Teaching (CLT) has quickly become popular in Vietnam (Pham, 2005, p 2) In accordance with the popularity of CLT in the country, it seems that the only use of English in ELT is widely supported However, the English-only view has recently been strongly criticized Many scholars have argued that the English-only pedagogy is ideological and that the use of the students‘ mother tongue in the second language classroom is both facilitative and motivational While Vietnamese teachers of English tend to use Vietnamese more than English in the English language classroom (Nguyen, 2006), there has been little research on the issue of teachers‘ opinions of the use of Vietnamese in teaching English Hence, the issue remains controversial among Vietnamese teachers of English as well as inspectors, teacher educators and school administrators(Nguyen, 2006) This paper is aimed to gain understanding of the attitudes to, and perceptions of, the use of Vietnamese in English language lessons held by a group of ELT teachers working in a Vietnamese high school with a view to clarifying further the issue from the teachers‘ perspectives The aim of the study Within the framework of a minor thesis, the aim of the study is to investigate the teachers‘ use of Vietnamese as well as their reasoning for the use of Vietnamese in teaching English at An Duong high school Thus, the objectives of the study are as follows: a Exploring teacher‘s use of Vietnamese in their English language classes as well as their pedagogical purposes of using Vietnamese in teaching English ; b Finding out students‘ and teachers‘ attitudes to the use of Vietnamese in their English classes and the differences between these two groups in their attitudes to the use of Vietnamese Research questions In order to achieve the above-stated aims and objectives, the study is designed to find answers to the following research questions: How often teachers use Vietnamese to teach English and what are their pedagogical purposes of using Vietnamese? To what extent teachers and students differ regarding their attitudes toward the use of Vietnamese in English lessons? Scope of the study This study is designed to gain understandings about the actual use of Vietnamese in English classrooms by the teachers and their attitudes as well as their students‘ attitudes to the use of Vietnamese in teaching and learning English The significance of the study The study will be a valuable reference not only for English teachers but also for all language instructors regarding the need to make a better-informed decision about what language to use or how to combine L1 and the new language when teaching English to high school students Also they would benefit from the lessons learnt from the project concerning teaching procedure As such the study would then be beneficial to the learners They would be better guided in comprehending vocabulary and grammar points, better perform in any tasks and hopefully could better use English in real life situations Design of the study The study is divided into three parts : the Introduction, the Development and the Conclusion Part A Introduction : deals with the rationale, aims, scope, methods and design of the study Part B Development : consists of chapters Chapter Literature Review is intended to give some theoretical background related to using L1 in l2 classes Chapter : The study presents the situation analysis, participants, data collection instruments, data collection procedures and data analysis The detailed results of the survey and comprehensive analysis on the data collected are focused Chapter Major findings and implications shows major findings and implications related to the teachers‘ use of L1 in L2 class Part C Conclusion : is a review of the study , limitations of the study and suggestions for further research PART B DEVELOPMENT CHAPTER LITERATURE REVIEW Introduction This chapter reviews the literature on the use of students‘ first language or mother tongue in teaching the second or foreign language The chapter begins with a brief review of the status of the students‘ mother tongue in various second or foreign language teaching methodology This is to create a theoretical background of the study This is followed by a review of the issue of students‘ first language or mother tongue in learning the second or foreign language from a bilingual education perspective The next point of the review is the debate about the use of the first language in the second language classes Finally, the literature on teachers‘ and students‘ attitudes to the use of the first language will be reviewed History of language teaching methods focusing on L1 use in L2 teaching A brief review of the literature related to language teaching methods shows that ―the role of L1 in L2 teaching‖ is ―one of the most long-standing controversies in the history of language pedagogy‖ (Stern, 1992, p 279) The following glimpse in the historical sequence of the most-recognized language teaching methods will highlight periodic changes in the role of L1 in L2 teaching The Grammar Translation Method derived from ―the teaching of the classical languages, Latin and Greek‖ over centuries (Larsen-Freeman, 1986, p 4) is the first one to be considered here In the early years of the nineteenth century in Western countries, the Grammar Translation Method dominated the L2 classroom During this period, L2 was taught through grammar illustration, bilingual vocabulary lists and translation exercises This method emphasizes on the literary language since its fundamental goal is to help learners be able to read literature written in L2, not to provide them with the ability to communicate verbally in L2 According to this method, L1 is freely used as ―a reference system‖ in the process of L2 acquisition (Stern, 1983, p 455) The majority of the teachers agreed that teachers just should use Vietnamese ‗sometimes‘ In other words, most of the respondents supported the limited use of L1, not the overuse of L1 This was consistent with the view made by Ellis (1984, cited in Mattioli, 2004), claiming that too much L1 use should be avoided because it could ―deprive the learners of valuable input in the L2‖ (p.15) The present study goes further in providing the following suggestions for the judicious use of Vietnamese in ELT: We can adjust the amount of Vietnamese to students‘ levels of English, - types of lessons and types of English we are teaching The higher students‘ level of English is, the less Vietnamese should be - used The frequency of teachers‘ use of Vietnamese depends on a lot of things - such as students‘ levels of English, aims of the lesson and duration of the class In Vietnam, the English levels of the students in the same class are not the same; therefore using some Vietnamese in ELT is useful for the weaker students If there is plenty of work that has to be finished in a short-time class, the teacher may use Vietnamese more than usual The amount of Vietnamese used by teachers should vary by students‘ - levels of English These above comments implies that according to the teacher participants, the judicious use of L1 by teachers could not be the same universally because it was influenced by specific factors in specific English classrooms This was in line with the claim made by Edstrom (2006) that ―judicious L1 use will likely look different in different classrooms‖ (p 289) It can be concluded that the use of L1 is a way of life in an EFL classroom Teachers in this study did use L1 for some purposes in their teaching and the frequency of their use of Vietnamese was not too much against their use of English in the classroom Both teachers and students seemed to be positive about the use of Vietnamese for purposes such as explaining complicated 33 grammar items………… It is interesting to note that teachers in this study did not support the idea of using too much Vietnamese in teaching English 3.2 Implications The findings from the study raise the issue of considering the employment of mother tongue, Vietnamese, in teaching English to students at An Duong high school in particular and in language teaching contexts in general Influenced by foreign trend and too anxious to reap success many teachers in Vietnam turn to L2 only policy In fact this has been considered a miracle that is expected to bring the most desirable dream for language learners: mastering the L2 in the shortest possible time The policy could be successful in some granted high schools such as Tran Phu granted high school in Hai phong What lies behind their success is the fact that the learners are supposed to be at pre-intermediate or intermediate level but have already been equipped with profound knowledge of grammar and vocabulary Their focus now is the mastery of the four skills However as confirmed by this study L2 does not always ensure success with the learners who are weak in both language input and skill development L1, with its own strength, could be an ingredient for the lesson‘s effectiveness, especially with complicated areas as grammar and vocabulary where abundance of careful instruction is required The result of the study also suggests that following the right procedure is important in a language lesson and that the learners could only learn best when they are encouraged and facilitated with the right instruction medium to think, discuss, use and negotiate uses of the new language It should be noted that the choice of the instruction medium should rely on the learners‘ response Whatever the teacher chooses, he/ she should sense what could generate the best interest , involve the learners the best, and create the most relaxed atmosphere These indicators are more important than any level of L2 exposure The research suggests that learners who are highly motivated and directed by their desire to work with English would prefer the teachers to use L2 whenever possible This indicates that even in stages of eliciting, 34 explaining, responding to grammar and vocabulary related problems, the use of L2 should be considered Another implication from this study is the language level factor While the use of L1 should be advocated for the subjects at low levels i.e elementary or pre-intermediate, the employment of the mother tongue should be considered carefully for the learners who are at higher level of proficiency It is suggested that a sensitive combination of the two languages should be there to ease out the learning process 35 PART C CONCLUSION Summary of the study The result of this study revealed that the use of Vietnamese was an unavoidable phenomenon in many Vietnamese high schools in general and at An Duong high school in particular The teachers‘ use of Vietnamese appeared to be systematic, though there were a few cases in which they did not make the best use of it The teachers were aware of the disadvantages of the excessive use of Vietnamese as their use of Vietnamese depended on the students‘ specific needs most of the time They preferred to use it with low achieving students to help them understand the new language Moreover, the study revealed some situations for which the teachers used Vietnamese such as explaining grammatical items, introducing new vocabulary, giving instruction and some other situations In the light of the findings, the researcher recommends that teachers should be very flexible when considering the language for instruction as they may increase their learners‘ interest, enthusiasm with the foreign language learning, concentration, and enjoyment during class It is significant for the teachers to realize that one criterion for the selection of instruction medium should be their effect in teaching Limitations The results in this thesis revealed that the use of Vietnamese is quite effective in teaching English to students at An Duong high school However, the small size of the sample does not necessarily ensure the generalizability of this finding In other words, caution should be taken in attempts to generalize what has been achieved here to a larger population The length of the research also poses another reservation for those considering the project and the practicality of its findings Suggestions for further research The following directions should be taken into consideration in the further research 36 First of all, this study should serve only as a preliminary project A further direction to follow should lie in the use of Vietnamese in teaching English to a larger sample Another direction could be examination of other uses of L1, for example, to manage class, to create teacher or student rapport These areas certainly promise to bring about interesting and beneficial findings 37 REFERENCES Atkinson, D (1987) The mother tongue in the classroom: A neglected source? ELT Journal, 41(4), 241-247 Auer Bach, E (1993 ) Article : Reexamining English only in the EFL classroom TESOL Quarterly 27,1 British Council (2004) Vote on mother tongue in forum teaching English Retrieved from www.teachingenglish.org.uk/talk/vote 15mother-tongue.html Brown, H.D (2000) Principles of language learning and teaching (4th ed.) San Francisco: Longman Cook, V (1999) Going beyond the native speaker in language teaching TESOL Quarterly, 33(2), 185-209 Cook, V (2001) Using the first language in the classroom The Canadian Modern Language Review 57(3), 402-423 Dulay, H., Burt, M & Krashen, S ( 1982 ) Language two New York : Oxford University Press Edstrom, A (2006) L1 use in the L2 classroom: One teacher‘s selfevaluation The Canadian Modern Language Review 63(2), 275-292 Ellis, R.(1997 ) Second language acquisition OUP, Oxford 10 Ferrer, V ( 2002 ) The mother tongue in the classroom Retrieved from http://www.teachingenglishworldwide.com 11 Harbord, J ( 1992) The use of the mother tongue in the classroom ELT Journal, (46/4: 30 45) 12 Harmer, J ( 1987) Teaching and learning grammar London : Longman 13 Harmer, J ( 1997) The practice of English language teaching London : Longman 14 Haycraft, J ( 1978) An introduction to English language teaching London: Longman 15 Howatt, A.( 1984) A history of English language teaching Oxford: Oxford University Press 38 16 Krashen, S (1981) Second language acquisition and second language learning Oxford: Pergamon 17 Larsen-Freeman, D (1986) Techniques and principles in language teaching Oxford: Oxford University Press 18 Lightbowm, P.M and Spada, N ( 2000) How languages are learned China: Oxford University Press 19 Miles, R (2004) Evaluating the use of L1 in the English language classroom (Master thesis, University of Birmingham, 2004) Retrieved from www.cels.bham.ac.uk/resources/essays/Milesdiss.pdf 20 Nunan, D and Lamb, C ( 1996) The self-directed teacher Cambridge : Cambridge University Press 21 Nunan, D.( 1999) Second language Teaching and Learning Heinle&Heinle 22 Prodromou, L.(2000) From Mother Tongue to Other Tongue Bridges Retrieved on http://www.thracenet.gr/bridges/bridges 23 Prodromou, L.(2002) The Role of the Mother Tongue in the Classroom IATEFL Issues April-May, 2002 24 Rodgers, S T ( 2001) Language Teaching Methodology Retrieved on http://www.cal.org/resources/digest/rodgers.html 25 Schweers, W Jr (1999) Using L1 in the L2 classroom English Teaching Forum 26 Sterm H.H (1983) Fundamental concepts of language teaching: Oxford University Press 27 Tang, J (2002) Using L1 in the English classroom English Teaching Forum, 40(1) Retrieved November 22, 2007 from http://exchanges.state.gov/forum/vols/vol40/no1/p36.html 28 Zacharias, N T (2003) A survey of tertiary teachers’ beliefs about English Language Teaching in Indonesia with regard to the role of English as a global language (Master thesis, Assumption University, 2003) Retrieved from http://www.asian-efl-journal.com/thesis.php 39 29 Zacharias, N T (2004) Teachers’ beliefs about the use of the learners’ mother tongue: A survey of Tertiary English Teachers in Indonesia Retrieved on http://www.englishaustralia.com.au 40 APPENDICES APPENDIX QUESTIONNAIRE FOR TEACHERS This survey questionnaire is designed for the study on teacher’s use of Vietnamese in English classrooms at An Duong high school Your assistance in completing the following items is highly appreciated All the information provided by you is of great use and solely for the study purpose Thank you! Please circle the answer where necessary Part I Personal information Your gender a Male b Female Your age a Under 25 b From 26- 35 c From 36-45 d Over 45 Years of teaching English a From 1-3 years b From 3- years c From 6- 10 years d Over 10 years Part II Teachers’ opinion on using Vietnamese in English classrooms at An Duong high school a Should Vietnamese be used in the classroom? Yes b No I When you think it is necessary to use Vietnamese in the English classroom? a to explain complex grammar points b to help define some new vocabulary items c to explain difficult concepts or ideas in reading and listening texts d to explain the meaning and the use of lexical chunks and idiomatic expressions e to give instructions f to give suggestions on how to learn more effectively If you think the use of Vietnamese is necessary in the classroom, why? a It aids comprehension greatly b It is more effective c It is less time-consuming 4.Do you believe using Vietnamese in your English class help your students learn this language? a A lot b Fairly much c A little d No II APPENDIX QUESTIONNAIRE FOR STUDENTS This survey questionnaire is designed for the study on teacher’s use of Vietnamese in English classrooms at An Duong high school Your assistance in completing the following items is highly appreciated All the information provided by you is of great use and solely for the study purpose Thank you! Please circle the answer where necessary Part I Personal information Your gender a Male b Female Your hometown a Village b Town How long have you been learning English? years You average mark in English in the first term of this school year: …………………………………………………………………… Part II Students’ attitudes towards teachers’ use of Vietnamese in English lessons at An Duong high school Should Vietnamese be used in the classroom? a Yes b No Do you like your teacher to use Vietnamese in the class? a Sometimes b A little c A lot d Not at all III When you think it is necessary to use Vietnamese in the English classroom? a to explain complex grammar points b to help define some new vocabulary items c to explain difficult concepts or ideas d to practice the use of lexical phrases and idiomatic expressions e to give instructions f to give suggestions on how to learn more effectively If you think the use of Vietnamese is necessary in the classroom, why? a It helps me to understand the difficult concepts better b It helps me to understand the new vocabulary items better c It makes me feel at ease, comfortable and less stressed d I feel less lost 5.Do you think the use of Vietnamese in the classroom helps you learn this language? a A lot b Fairly much c A little d Not at all How often you think Vietnamese should be used in the classroom? a Fairly frequently b Sometimes c Very rarely d Never 7.What percentage of time you think Vietnamese should be used in the class? Time Response IV PHIẾU ĐIỀU TRA NGHIÊN CỨU Bảng câu hỏi dùng cho việc nghiên cứu việc sử dụng tiếng Việt giáo viên học ngoại ngữ trường THPT An Dương Tôi đánh giá cao giúp đỡ em thơng qua việc hồn thành bảng câu hỏi Tất thông tin em cung cấp hữu dụng dành riêng cho mục đích nghiên cứu Cảm ơn em! Hãy khoanh tròn đáp án em cho Phần I Thơng tin cá nhân Giới tính a Nam b Nữ Nơi cư trú a Vùng nông thôn b Thị Trấn Em học tiếng Anh bao lâu? .năm Điểm trung bình mơn tiếng Anh học kì :……… Phần II Ý kiến học sinh việc giáo viên sử dụng tiếng Việt giảng dạy tiếng Anh trường THPT An Dương Có nên sử dụng tiếng Việt học ngoại ngũ khơng? Có Khơng Bạn có muốn (thầy) giáo sử dụng tiếng Việt để giáng không? a Thỉnh thoảng b Một chút c Nhiều d Hồn tồn khơng Bạn nghĩ cần phải sử dụng tiếng Việt học tiếng Anh? a Giảng giải phần ngữ pháp phức tạp b Hỗ trợ tìm hiểu từ vựng c Giảng giải khái niệm khó hiểu đọc nghe d Giải thích cụm từ thành ngữ e Hướng dẫn học f Gợi ý cách học hiệu 4.Tại bạn cho việc sử dụng tiếng Việt học tiếng Anh cần thiết ? a Sử dụng tiếng Việt giúp hiểu khái niệm khó tốt b Sử dụng tiếng Việt giúp hiểu từ vựng tốt c Sử dụng tiếng Việt khiến cảm thấy thoải mái đỡ căng thẳng a b V d Tôi cảm thấy hiểu đầy đủ Sử dụng tiếng Việt giúp bạn học tiếng Anh nào? a Nhiều b Khá nhiều c Một chút d Hồn tồn khơng Theo bạn, tiếng Việt nên sử dụng với tần suất nào? a Tương đối thường xuyên b Thỉnh thoảng c Rất d Không Thời gian sử dụng tiếng Việt học tiếng Anh a % b 10 % c 20 % d 30 % VI APPENDIX INTERVIEW QUESTIONS Interviewee:…………………………………………………………… Intended duration: ……………………… minutes Date:……………………………………… Location:………………………………… Do you think teachers should use Vietnamese in English classes? If not, why should not teachers use Vietnamese in English classes? If yes, in what situations teachers should use Vietnamese in English classes? (Prompts: explaining new words/explaining grammatical points/giving instructions…) (Prompts: in what situations it is especially advisable for teachers to use Vietnamese?) Why should teachers use Vietnamese in these situations? ( Benefits that the use of Vietnamese can bring about) (Prompts: help students understand better/save time…) How often should teachers use Vietnamese in English classes? ( When you use English and when you use Vietnamese in your English lessons?) (Prompts: rarely/sometimes/frequently….) VII ... accomplished, accompany, and discarded following her English explanations In explaining the word accompany , she came up with an appropriate and culturally specific Vietnamese translation, and the... be immersed in L2 through the use of L2 ―as a means of instruction and communication in the language classroom‖, and through ―the avoidance of the use of L1 and of translation as a technique‖... in the process of teaching L2 including explaining the meaning of new words and grammatical points, giving instructions, checking learners‘ understanding and giving feedback to individual learners

Ngày đăng: 08/11/2020, 12:10

Từ khóa liên quan

Tài liệu cùng người dùng

  • Đang cập nhật ...

Tài liệu liên quan