I'm wondering why that might be necessary? More to the point, I think it should be recognised - in terms of English as an international language, English is continually being reinvented as it is being used to communicate. Therefore, if 'slang or mother tongue influence' 'interferes', and it results in mis-communication, then it should be acknowledged. If it aids in communication, for example with other ESL speakers, then is it a problem? Sometimes communication confidence and competence will be improved in the process - better than seeing it as a deficit.
I'm wondering why that might be necessary? More to the point, I think it should be recognised - in terms of English as an international language, English is continually being reinvented as it is being used to communicate. Therefore, if 'slang or mother tongue influence' 'interferes', and it results in mis-communication, then it should be acknowledged. If it aids in communication, for example with other ESL speakers, then is it a problem? Sometimes communication confidence and competence will be improved in the process - better than seeing it as a deficit.
Attend English Medium schools from the young age. use English Language Laboratory service. Hire the services of English Tutors from Englan d Use internet English library or Encarta Library with pronunciation aids. Get friends who are English speakers to teach and instruct you English literacy
Perhaps you are inquiring in how to become more proficient? If that is so, the more access to native speakers and interactions (e.g., social media, tv, movies, music, etc.) are ideal. Slang then can become evidence of knowledge of the new language, the ability to know and speak like the locals. Good luck!
You can get proficiency in speaking english by practice but Cartoon programmes for kids also are useful source of speaking style at the initial level how to speak.Moreover you also can listen many audio programmes online or via app for understanding the language style how to speak.