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Question 1

how to choose the tense? (present perfect or past simple)

Answer 1

1. has the time period finished?
   (PP is used when the time period has not finished; PS is used when the time period has finished)
2. is it new or old information?
   (PP - recent news, PS - older information)
3. is it specific time?
   (PP - time is not specified, PS - time is clear)
4. has the action finished?
   (PP is used with for and since when the actions have not finished yet; PS is used with for when the actions have already finished)