a. Mother-Tongue Interference
Although  young  children  appear  to  be  able  to  learn  a foreign language quite easily and to produce a new sound very
effectively,  older  and  learners  experience  considerable difficulty. These  all problem are  not out of the  interference of
the  mother-tongue.  Like  stated  by  Wilkins  on  Linguistics  in Learning  Teaching  has  made  some  related observation  to  this
problem.  He  said  that  “When  learning  a  foreign  language  an individual  already  knows  his  mother-tongue,  and  it  is  this
which  he  attempts  to  transfer.  The  transfer  may  prove  to  be justified because the structure of the two languages is similar-in
that  cases  get  ‘positive-transfer’  or  ‘facilitation’-or  it  may prove unjustified because the structure of the two languages are
different-in  that  case  we  get  ‘negative  –transfer’  or ‘interference’.
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From  the  explanation  above,  the  writer  concludes  that the  errors  made  Indonesians  who  learn  English  as  foreign
language are normal problems, since they are going to struggle to control their mother-tongue interference.
b. Overgeneralization
Overgeneralization  is  a  process  that  occurs  as  the second  language  learner  acts  within  the  target  language,
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Available  at  www.  Melta  .org.myET1996main4.html,  accessed  on  September  12, 2008
generalizing  a  particular  rule  or  item  in  the  second  language- irrespective  of  native  language-beyond  legitimate  bounds.
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Richard  also  stated  on  A  Non-Contrastive  Approach  to  Error Analysis  and  explains  that  overgeneralization  covers  instance
where the learner creates a deviant structure on the basis of his experiences in the target language.
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From  this,  the  writer  has  a  great  consideration  that overgeneralization is a natural problem that usually happens in
anyone  learning  foreign  language.  Because  some  patterns  and structures  that  may  be  there  in  foreign  language  but  there  are
not in any other languages.
c. Errors encouraged by teaching material or method