Chapter Five is the conclusion part, which is composed of the major findings of the paper and some pedagogical implications, as well as the limitations of the present study。

Chapter Two Literature Review

2。1 Definition of Errors

Making errors is a normal and indispensable part in the process of learning a language。 In defining errors, different researchers gave their own definition from different levels of language。 According to Corder (1973), the deficiency of the learner' ability resulted in errors, which appeared as a discrepancy between language learners and native speakers。 Rod Ellis (1999) considered error as a deviation from the norms of the target language。 Firedenberg (1991) further stated that errors were deviations from the target language in many aspects such as pronunciation, structure and the use of vocabulary。 As for Richards (2002), he thought that error was used as a linguistic item in the process of speaking or writing of another language, showing learners' faulty or incomplete learning。 Although different researchers gave different definitions of errors, they had something in common, which regarded errors as deviations from the target language。 It is worth noting that such kind of deviation can be further pided into errors and mistakes。 文献综述

Corder (1967) first proposed errors and mistakes when analyzing errors。 He stated that the emergence of errors resulted from language learners' lack of knowledge, which indicated that they were not able to fully master and internalize language rules, and it suggested failure in competence。 It is unintentional for language learners to make errors。 Nevertheless, errors turn out to be systematic and they can't be corrected by learners themselves。 As for mistakes, they have nothing to do with the competence but the learner's failure in performance。 It represents occasional lapses in performance, for example, a slip of tongue。 Though the learners have already learned the knowledge, they still fail to function correctly due to some factors such as poor memory, physical or psychological conditions。 In addition, mistakes are not systematic, and they can be self-corrected once they are pointed out。

As far as this paper concerned, the author takes every deviation from the target language into account, no matter errors or mistakes。 And the paper uses the term "error" in every case。

2。2 Classification of Errors 

Many researchers attempt to classify errors and Corder (1967) first distinguished errors from mistakes。 Later, he pided errors into errors of competence and errors of performance, and further pided errors of competence into interlingual errors and intralingual errors, thus established the theoretical framework of error analysis。 

It is of great importance to differentiate between interlingual errors and intralingual errors。 On the one hand, interlingual errors are mainly regarded as the language errors caused by interference of native language to the target language。 On the other hand, intralingual errors refer to the errors caused in the process of learning target language rules。 For instance, after learning a certain grammar rule, the learners don't understand the rule sufficiently, thus they apply it in other ways mistakenly。 

With Corder's further research on the theories of errors, he also pided errors into expressive errors and receptive errors (Corder, 1973)。 However, he was still not satisfied with these classifications。 Therefore, he worked with Allen to come up with another classification, and that is pre-systematic errors, systematic errors and post-systematic errors (Allen & Corder, 1974)。

Except Corder's classifications of errors, there are also classifications made by other researchers。 As for James (1998), he classified errors into four categories according to the causes of errors: intralingual errors caused by target language, interlingual errors influenced by mother tongue, communication strategy based errors, and more, induced errors。 It is worth noting that Richards (1971) further pided intraligual errors into overgeneralization, ignorance of rule restrictions, incomplete application of rules and false concepts hypothesized。