The Concept of Present Perfect
Just
Very Recent
I've just finished it.
Already
No Need to Repeat
Present result
Earlier than planned
Yet
Mostly used in questions and negatives.
Uncompleted Actions
She hasn't finished her homework yet.
I haven't seen this movie yet.
Have they arrived yet?
Ever
Questions
Have you ever eaten snail?
Superlatives
It's the most dangerous thing I've ever done.
The worst
The best
Negatives
We've never ever heard about this guy.
Never
Experiences
I've never read this book.
Negative
Future possibility
Since
When used with present perfect means: from a point in past up to the present moment.
November
Last year
I was a kid
2004
