Monday, November 12, 2012

Simple past vs present perfect: some rules and examples



Some students find it difficult to decide when to use the simple past tense or the past perfect. Here are some rules and examples. Remember if you specify a time in the past (a date, an hour of the day, etc), you use the simple past. 

1 Has the time period finished?
Rule
Example
Explanation
The present perfect is used when the time period has NOT finished.
I have seen three movies this week.
(This week has not finished yet.)
The simple past is used when the time period HAS finished.
I saw three movies last week.
(Last week has finished.)
2 Is it new information or old?
Rule
Example
Explanation
The present perfect is often used when giving recent news.
Martin has crashed his car again.
(This is new info.)
The simple past is used when giving older information.
Martin crashed his car last year.
(This is old info.)
3 Is it a specific time?
Rule
Example
Explanation
The present perfect is used when the time is not specific.
I have seen that movie already.
(We don't know when.)
The simple past is used when the time is clear.
I saw that movie on Thursday.
(We know exactly when.)
4 Has the action finished (sentences with “for” or “since”)?
Rule
Example
Explanation
The present perfect is used with for and since, when the actions have not finished yet.
I have lived in Victoria for five years.
(I still live in Victoria.)
The simple past is used with for and since, when the actions have already finished.
I lived in Victoria for five years.
(I don't live in Victoria now.)

Reference; University of Victoria, Canada
For more practice: http://web2.uvcs.uvic.ca/elc/studyzone/410/grammar/ppvpast.htm

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