1、StudyonSynonymsBasedonCOCA：CommonSynonyms“Assure”and【Abstract】In this paper， the author tends to make an empirical study on analysis of synonyms of two words based on Corpus of Contemporary American EnglishCOCA. As COCA has large corpus reserves， thus providing a reliable method for summarizing char
2、acteristics of synonyms from examples for English learners. It is apparently proved that COCA has a directive significance in reflecting characteristics of synonyms in word frequency distribution， grammatical structure and collocation . 【Key words】empirical study； COCA； Synonyms； “assure” and “ensur
3、e” 1. The Characteristics of COCA The last 20 years have witnessed the revival of corpus linguistics in China， which is characteristics by the empirical approaches for quantitative and qualitative analysis of large collections of natural texts in authentic use. Corpus is a powerful tool to study cor
4、pus linguistics. In COCA， the corpus involved five filed， that is， spoken， fiction， popular magazine， newspapers， and academic journals. This composition holds for the corpus overall which gives a variety of sources. In conclusion， COCA has the following characteristics： First， it is freely open for
5、 users as long as registering on line. Second， COCA belongs to monitor corpus， which can reflect language changes as it updated and developed constantly. Third， COCA has balanced corpus as it has nearly equally five field. 2. Analysis of the Differences between “Assure” and “Ensure” Based on COCA 2.
6、1 Distributions of Two Words Frequency among Different Registers In actual language activities， people use different varieties of language styles or choose certain words because of the communication aims， different occupation or interests and so on. Synonyms have detonation and connotation differenc
7、e， so they show various distribution characteristics in different genre. When using COCA， we can find the different using methods of two words by analyzing data. According to the “Chart” function in COCA， we can get the frequency and occurrences of two words in different language styles. Next， look
8、at the frequency distribution of the two words “assure” and “ensure” in charters. From the above two charters， it is easy to get the following table： From the table， we can find that， all the occurrence of “ensure” is nearly 3.5 times（18852/5437） that of “assure” ，so we can get the conclusion that i
9、n American English， “ensure” is more often to use than “assure”. But in the sub-section of magazine， newspaper and academic， the occurrence of the two words has the apparent difference. For example， the occurrence of “ensure” is more than 6 times （8893/1377）than “assure” in the section of academic，
10、thus we can reach a conclusion that “ensure” is more formal than “assure” in the academic papers. In addition， according to the function of “chart”， we can get diachronic changes of the two words. Look at the following two charts. For the tendency of the diachronic changes， we can find that， “assure
11、” shows a downward trend with time goes on. But for “ensure”， there is a rising trend in using with time goes on. Understanding the diachronic changes of the two words has the guiding significance for learners. 2.2 Differences in Pronoun Collocation of Two Words Look at the form the author had produ
12、ced according to the pronoun collocation. From the above form， we can found that， pronoun is tendency to allocate with“assure” compared with “ensure”. And except the pronoun “she”， other pronouns have an apparent tendency to collocate with “assure” .On the other hand， “assure” and “ensure ” both col
13、locates much more with “you” and “I” than other pronouns. 3. Conclusion The conclusions are： First， in American English， “ensure” is more often used than “assure”. Second， “assure” dont have apparent language genre ，but “ensure” does have one. Third， in the past 20 years， the usage frequency of “ass
14、ure” is decline but that of “ensure” is rising as time goes on. Fourth， “assure” is more tendency to collocate with pronouns than “ensure”. It is apparently proved that COCA has a unique advantages reflecting characteristics of synonyms. References： 1Lyons.J.Linguistic Semantic：An Introduction.Cambridge： Cambridge University Press.1995.
