Present Perfect - just, already, yet, still
just = a short time ago
(only in affirmative sentences, always between the auxiliary verb and the past participle)
A: Would like like something to eat?
B: No, thanks. I've just had dinner.
already = before expected
(only in affirmative sentences, always between the auxiliary verb and the past participle)
Mum: Dinner!
Son: I've already had dinner.
yet = until now
(only in negative sentences and questions, always at the end of them)
I haven't had dinner yet.
Have you had dinner yet?
BONUS
still = continues up to a time
She still hasn't phoned me.
I still haven't had dinner.
They are still learning at school. (the present continuous)
We will still be on holiday. (future simple)
