Brown(2000) points that error and mistake are two very different phenomena and mistake must be carefully distinguished from errors of a second language learner。 He refers to mistake as a performance error which is a failure to use a known system correctly。 All people make mistakes, in both native and second language situations。 He defines error as an obvious deviation from the grammar of native speakers。 

According to Dai Weidong and He Zhaoxiong(2013), errors are defined as unintentional deviants from the target language and not self-corrigible by the learner。 Errors suggest failure in competence while mistakes are defined as deviant forms and self-corrigible, which suggest failures in performance。

However, it is not easy to make a distinction between error and mistake, because the learners’ capacity to self-correction is objectively observable only if the learners actually self-correct(Brown, 2000)。 Thus, in this study, the lexical errors have been collected include both mistakes and errors。 文献综述

2。1。3 Significances of Error

In the traditional teaching and learning, error was considered as a sign of the inadequate teaching techniques and a failure of language learning。 However, this concept has changed after the publication of Corder’s paper named The Significance of Learner’ Errors。 

According to Corder(1967), errors are significant in three different ways。 Firstly, errors can tell teachers what remains to learn。 Secondly, errors provide researchers with evidence of how language is acquired and what strategies are employed in language learning。 Thirdly and the most importantly, they are essential to the learner as it can test his hypotheses about the nature of the language he is learning。 

It indicates that the errors are significant in telling the teacher what needs to be taught, in telling the researcher how learning proceeds and those errors are a means whereby learners test their hypotheses about the language to be learnt (Dai Weidong& He zhaoxiong, 2013)。