1. 研究目的与意义（文献综述包含参考文献）

in his second language acquisition (sla) theory, krashen points out that there are two main ways to improve learners foreign language proficiency: language learning and language acquisition. the former one refers to the conscious learning of foreign language knowledge (including grammar, rules, pronunciation and vocabulary knowledge); while the latter one is similar to the acquisition of a mother tongue by children, which is obtained through natural communication of language. according to krashen, language learning is based on a sufficient amount of comprehensible language input (reading and listening). reading and listening, as comprehension skills, are the channels to acquire language knowledge and indispensable ways to lay a solid foundation of language. they are also the premises of language output like speaking, writing and translating.many researchers have tried to give a thorough definition of l2 proficiency, but it is still one of the most poorly defined concepts in the field of language testing. the ideas about that vary from scholar to scholar. therefore, the l2 proficiency is measured by some authoritative tests. in china, the most recognized english proficiency tests are cet and tem tests. the cet test is used for measuring college students overall english proficiency as well as their listening, writing, reading ability. it will be a good chance to study the effects of these constructs on l2 proficiency according to their test results.1.literature review1.1definitions of key termslanguage proficiency is widely known as one of the most poorly defined concepts in the field of language testing. it is defined as the language learners ability by clark (1972). but other scholars have their different ideas. theoretically, it is not easy to define language proficiency because it is relevant to various factors such as language ability, language awareness and the ability of listening, speaking, reading and writing in an appropriate context. however, practically, both abroad and domestic researchers measure the second language (l2) proficiency according to some authoritative tests, such as the test of english as a foreign language (toefl), the international english language testing system (ielts), college english test (cet) and test for english majors (tem).1.2 l2 listeninglistening is a comprehension process which involves receiving and deciphering linguistic input. it is also regarded as the most implicit and least explicit language skills to tackle with (hulstijn, 2003), presenting a considerable challenge to both efl and esl learners. second language listening is continuously thought as one of the most difficult skills to learn by l2 learners (vandergrift goh, 2012). however, comparing with other language skills, l2 listening is most frequently used in second language instruction, because it contributes more to l2 academic success even than reading skills do (rost, 2013).1.3 l2 reading reading is an important activity of human society, which comes into being with the production of words. with the help of words, the sound information of language can be transformed into visual information, which can be preserved for a long time (zhang biyin, 1992). human relies on reading as a necessary process and means to form cognition. that is to say, it is difficult for people to form a complete cognition without reading. downing and leong (1982) defined reading as the interpretation of sign. reading is a multi-faceted, complex construct. and the complexity increases when it comes to second language (l2) reading. in many second and foreign language curricula, reading is commonly offered for different age groups. yet, it is still a skill not easily acquired by learners.1.4 l2 writingl2 writing encompasses a remarkably complex and variable set of behaviors. writing is an expressive and productive language skill. compared with listening, speaking and reading, it is more demanding for learners. as an important indicator to measure college students' comprehensive english proficiency and application ability, it requires learners to select words accurately, write sentences in a standard way. what is more, learners should have a clear main idea, and organize articles logically. these requirements also examine learners' ability to master vocabulary, grammar, and their logical thinking. previous studies have mainly focused on the relationship between l1 writing ability, l2 proficiency and l2 writing ability (cumming, 1989; sasaki bernhardt, 1991) interpret l2 linguistic knowledge as l2 vocabulary knowledge and l2 grammatical knowledge. following their examples, most linguistic knowledge tests focus on subjects lexical and syntactic knowledge. therefore, to ordinary language learners, the acquisition of vocabulary and grammar has long been felt to be a significant component of learning a foreign language because it is crucial for their success in these tests.1.5 overview of previous studies1.6 research gapover the past decades, many empirical research have focused on detailed studies about l2 listening, l2 reading and l2 writing. the relationships between these factors are also attracting scholars attention. however, there is still very little research that provides empirical evidence for the relationship among all these factors. therefore, further research should be done to provide a more comprehensive and systematic understanding of the constructs of cet-6 proficiency.1.7 research purposesthe present study aims to investigate the effects of four constructs, namely l2 listening, l2 reading, l2 writing and l2 linguistic knowledge on l2 proficiency by analyzing the data collected from 2537 college students cet-6 test results. the test consists of four parts, writing, listening comprehension, reading comprehension and linguistic knowledge. scores of each part will be collected separately. then the software amos (analysis of moment structures) will be used for data analysis. the effects of constructs on cet-6 proficiency will be worked out by a measurement model and the relationship between each pair of constructs can be figured out through the analysis of correlation.referencesbernhardt, e. (1991). reading development in a second language. norwood, nj: ablex publishing corporation.bachman, l. f. (2000). modern language testing at the turn of the century: assuring that what we count counts. language testing, 17, 1-42.bachman, l. f., spolsky, b. (1995). an investigation into the comparability of two tests of english as a foreign language. uk: cambridge university press.campbell, c. (2004). teaching second language writing: interacting with text. beijing: foreign language teaching and research press.carroll, j. b. (1961). fundamental consideration in testing for english language proficiency of foreign students. in h. b. allen (ed.), teaching english as a second: a book of reading. new york: mcgraw hill book company.cumming, a (1989). writing expertise and second language proficiency. language learning, 39, 81-141.downing, j., che kan leong. (1982). psychology of reading. new york, ny: macmillan.fouly, k. a., bachman, l. f. cziko, g. a. (1990). the divisibility of language competence: a confirmatory approach. language learning, 40, 1-21.grabe, w., stoller, f. (2013). teaching and researching reading (2nd ed.). new york, ny: routledge.henry, a, r. (1993). second language rhetoric in process: a comparison of arabic, chinese and spanish. new york: peter lang.hulstijn, j. h. (2003). connectionist models of language processing and the training of listening skills with the aid of multimedia software. computer assisted language learning, 16, 423-25.krashen, s. (1984). writing: research, theory, and application. oxford: pegramon institute of english.lee, j. w., schallert, d. (1997). the relative contribution of l2 language proficiency and l1 reading ability to l2 reading performance: a test of the threshold hypothesis in an efl context. tesol quarterly, 31, 713-739.oller, j. w. (1979). the factorial structure of language proficiency: divisible or not? language test at school: a pragmatic approach. london: longman, 423-458.sasaki, m. k. hirose. (1996). explanatory variables for efl students expository writing. language learning, 46, 137-174.vandergrift, l. (2006). second language listening: listening ability or language proficiency? the modern language journal, 90, 6-18.vandergrift, l., goh, c. (2012). teaching and learning second language listening: metacognition in action. new york, ny: routledge.voller, h. j. (1983). the structure of foreign language competence. in a. hughes, d. porter (ed.), current development in language testing. london: academic press, 3-29.widdowson，h. g. (1999). teaching language as communication. shanghai: shanghai foreign language education press.zamel, v. (1983). the composition process of advanced esl students: six case studies. tesol quarterly, 17, 165-187.马广惠、文秋芳（1999），大学生英语写作能力的影响因素研究。

《外语教学与研究》，04.荣泰生（2010），《amos与研究方法》。

重庆：重庆大学出版社。

2. 研究的基本内容、问题解决措施及方案

Data collectionThe subjects of this research are 2537 students from Nanjing Tech University covering 28 science and liberal arts majors. These students will receive the CET-6 test, which consists of four parts, namely, writing, reading comprehension, listening comprehension, cloze and translation. It takes altogether 125 minutes for students to complete this test. We collect these students CET-6 test results. Data analysisAfter collecting the data, the missing values are the first to be removed. Then, a measurement model is built and the data are analyzed by AMOS 22. Many indexes are checked to see whether the data fit the model. The effects of different factors on L2 proficiency can be figured out by the model. Whats more, the interrelationships among L2 listening, L2 reading, L2 writing and L2 linguistic knowledge are also assessed through the analysis of correlation using the same software.