I have been trying to learn English for 3 or 4 years. I worked previously in the Internet development business, but today I'm starting in a new area, real estate. Last friday I studied English with my teacher Jerry, he's awesome! Thank you everybody!

Past tense... (Trying to improve)

I have been trying to learn English for 3 or 4 years. In the past, I have worked in the area of Internet development area, but today I'm a beginner in my new area, Real Estate. Last friday I have studied English with my teacher Jerry. He's awesome! Thank you everybody!

I have studied English for a year.  Ainda é relevante agora. (Talvez ainda continua.)

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I studied English last friday.   Terminado.

Passado<----->                                   presente