Present perfect . Use 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”