Present perfect. U se present perfect + since/ for:to talk about actions and states which started in the past and are still true now. (acciones o estados que empezaron en el pasado y continuan siendo verdad o estando vigentes en el presente). “I have lived in Manchester for 20 years”=I came to live to Manchester 20 years ago and I live in Manchester now. Llevo viviendo 20 años en Manchester. “ I have taught at this school for 2 years”= I started teaching 2 years ago and I'm still teaching here). Llevo 2 años dando clase en esta escuela. Don't use PRESENT SIMPLE: I live in Manchester for 20 years. WRONG.

Present perfect - Use how long...?(Cuánto tiempo) to ask about the duration of an action or a state. Eg: A Where do you live? B in Manchester A How long have you lived there? B I've lived there for 20 years. A Where do you work? B In Manchester A How long have you worked there? B I've worked there since 2005.

PRESENT PERFECT+FOR  Use FOR for PERIOD OF TIME (We are considering its duration).  for 3 weeks, for 2 weeks, for 5 years, for a long time, for a month, for hours... Eg I've had this car for 3 weeks. I've worked here for 5 years. We have taught at this school for a long time. They have been married for a month.

PRESENT PERFECT+SINCE  Use SINCE with the BEGINNING of a PERIOD OF TIME. (We're considering its STARTING POINT).  Since 1990, since Wednesday, since I was a child, since yesterday, since this morning etc. Eg “He has lived here since 1990” “They have been at this hotel since Wednesday” “I've been afraid of snakes since I was a child”