... using AND, BUT, OR as cohesive devices faced by Vietnamese learners at high school. - Find the major causes and sources of error committed by high school students in the area of using AND, BUT, ... out.1.4.3.Error analysis 1.4.3.1.The concept of error analysis “ Error analysis is the process of determining the incidence, nature, cause, and consequences of unsuccessful language” ( in Errors in language ... Errors in language learning and use” _ Carl James).1.4.3.2.Significance of error analysis 1.4.3.3.Error analysis and contrastive analysis 1.4.4.Causes of errors in second language learning According...