PRESENT PERFECT: JUST, ALREADY, YET
The present perfect is used to indicate a link between the present and the past.
An action or situation that started in the past and continues in the present.
I have lived in Bristol since 1984 (= and I still do.)
An action performed during a period that has not yet finished.
She has been to the cinema twice this week (= and the week isn't over yet.)
A repeated action in an unspecified period between the past and now.
We have visited Portugal several times.
An action when the time is not important.
He has read 'War and Peace'. (= the result of his reading is important)
STRUCTURE:
-AFFIRMATIVE:
SUBJECT + TO HAVE + PAST PARTICIPLE
She has visited
-NEGATIVE:
SUBJECT + TO HAVE + NOT + PAST PARTICIPLE
She hasn’t visited
-INTERROGATIVE:
TO HAVE + SUBJECT + PAST PARTICIPLE + ?
Has she visited?