1. PAST SIMPLE vs PRESENT PERFECTvs
PRESENT PERFECT

2. When do we use each tense?
PAST SIMPLE
Use the Past Simple for an 
action or situation which 
happened in the past and is
over, finished, done.
e.g. I lived in Rosario five
years ago. But at the end of
last year I moved to Buenos
Aires.
PRESENT PERFECT
Use the Present Perfect for an 
 action that started in the past 
 but is still true today.
e.g. I have lived in Buenos
Aires for three months and I
have already made lots of
friends.

3. Use the Past Simple with time words like:
Use the Present Perfect with time words like:

4. heRE ARE SOME MORE NOTES ON PRESENT PERFECT
1. We use the Present Perfect to talk about things that happened in the past but we do not say exactly when they happened:
e.g. I've seen this film before. 
       I don't want to see it again.     
2. We use the Present Perfect to talk about our lives:
e. g. I've sailed across the Atlantic. I've seen elephants and giraffes in Africa.

5. 3. We use just with the present perfect to talk about things that happened a short time before now:  
e.g. The children have just finished school We often use the present perfect with never and ever:   e.g. Have you ever  driven a racing car?        No, I've never driven one,         but I would like to do so. 5. We use yet in questions and negative sentences.   e.g. Have you finished your exercise yet?        No, I haven't started it yet.

6. 6. We use already with the present perfect to show that something happened before it was expected to happen:  
e.g. Sue: Would you like to see the new Harry Potter film?
Tom: No, thanks. I have already seen it We often use the present perfect for actions that happened in the past and have a result now:  e.g. Your room looks different.
Have you painted it?    
   8. We use the present perfect for unfinished situations or actions which started in the past and continue now:   e.g. We’ve lived in this house since we got married. 
Alan has been an architect for ten years.

7. SINCE + point of time
FOR + a period of time
Since
2009
five o’clock
last week
I was 10 years old
three days ago
June 20th
Thursday
yesterday
January
last summer
lunch-time
For
six months
ages
a long time
two hours
over a month
ever
3 years
a century
a moment
ten minutes
six days