We use the present perfect tense:
- for something that started in the past and continues in the present:
oh! I have lost my phone!
- for something we have done several times in the past and continue to do
when we are talking about our experience up to the present
- for something that happened in the past but is important at the time of speaking
- We often use the present perfect with time adverbials which refer to the recent past(just, only just, recently)
or adverbials which include the present:
ever (in questions), so far, until now,up to now, yet (in questions and negatives).
- We do not use the present perfect with an adverbial which refers to past time which is finished.
The past tense in English is used:
- to talk about the past
- to talk about hypotheses – things that are imagined rather than true.
- for politeness.