When do we use the Present Perfect and when do we use the Past Simple?
PRESENT PERFECTThe present perfect tense is used :
- To talk about an action which started in the past and continues today :
For and since are used to express duration.
- I have lived here for 10 years. I have lived here since 2008.
(I arrived 10 years ago and I am still here.)
- To refer to past events in an unfinished period of time.
- I have written two letters today.
(Two letters are written but today is not finished.)
- To talk about recently completed actions with 'just'.
- "I've just finished reading the book you lent me."
- To refer to past events that have happened recently or have just been announced :
- There has been a plane crash near the coast.
(We know the event took place but we don't know when.)
- To talk about a past action with a result in the present:
- I've broken my arm. I can't drive (= because my arm is broken now.)
- To talk and ask about experiences or accomplishments up to the time of speaking :
- "I'm a writer. I've written 9 books."
- "Have you ever written a biography?" "No, never."
PAST SIMPLEThe Past Simple is used:
- When the period of time is finished.
- I wrote two letters yesterday. (Yesterday is finished).
- When the time is mentioned, either a precise time in the past, or a time expression which clearly situates the event in the past.
- John lived in the country
..... until the age of 6.
..... when he was young.
..... from 2004 to 2010
..... before he moved to London.
..... a long time ago.
As a general rule, if you can answer the question "when?", use the Past Simple.