To talk about past experiences when you
don't mention when they happened, e.g. Have
you ever met a famous person?
For finished actions which have present
results (no time specified) , e.g. I've lost my glasses!
With non-action verbs, e.g. be, have, know, like to say that
something started in the past and is still true now, e.g. We've
known each other since primary school.
With just, yet, already,e.g. I've just finished dinner.
With superlatives and the first,, second, last time, ...e.g.
It's the worst film I've ever seen!
It emphasizes the completion of an action,
e.g. I've studied for my exams.
Present Perfect
Continuous
Uses
To say that an action started in the past and is still hapenning now, usually
with 'How long...?, for or since, all day, etc. e.g., How long have you been
working in this office?
For repeated actions, usually with a time expression like all day / recently,
e.g. It's been raining all day.
For continuous actions that have just finished but which have present
results., e.g. I've been grading all morning. I'm exhausted!
It emphasizes the duration of an action, e.g. I've been studying for
my exams.