The Present Perfect is used to indicate a link between the present and the past. The time of the action is before now but not specified, and we are often more interested in the result than in the action itself.

Example: I have lost my pen (which implies I lost my pen and still have not found it. Note: The result is that тАЬI have still not found itтАЭ ; action is тАЬlosing of the penтАЭ; result is more important and so present perfect)



When we want to give or ask details about when, where, who, we use the simple past. Example: I lost my pen yesterday. (specific detail is given about when the action was done; more emphasis on action than on result; meaning = we donтАЩt know the result of losing th epen ie. have I found it or not; we ar einterested only in WHEN it was lost)



In conclusion:

The time makes all the difference. When you're not interested in when something happened, or if you don't know, you use the Present Perfect. However, if the time is important, or if you know when something happened, use the Past Simple.



Also:

Ever and never are used with the Present Perfect. Ever means "at some time in the past," and never means "at no time in the past."



And тАж

Always and never come before the main verb.

Example: He has never been late to work



A few times, several times, from time to time come at the end of the sentence.

Example: I have been late a few times.


hope this helps someone ... commens welcome