Has and Have are auxiliaries here, so you have to start with them in a question
(Have you already seen him?)
and in a negative sentence you add NOT after have or has.
(We haven’t written stories yet)
USE:
-
No TIME INDICATOR (like yesterday) in the sentence, but the action is finished
I have bought a new car!
She has been to Africa twice.
-
When one of these words is in the sentence: just/ already/ lately/ recently/ yet/ ever/ never
I have already done my homework.
She hasn’t seen her teacher yet.
+ ed (regular verbs)
Has/have + past participle:
3rd form (irregular verbs)
The Present Perfect
The past simple is also finished, but contains a time indicator. You know when it happened.
We went to the theater yesterday.
They worked hard last week.
To know whether you have to use the past simple or the present perfect, ask the question: WHEN DID IT HAPPEN?
If you know the answer use the past simple
If you don't know the answer use the present perfect.
A QUESTION WITH WHEN ASKS FOR A TIME INDICATOR, SO YOU MUST USE THE PAST. WITH A TIME INDICATOR YOU CANNOT USE HAVE OR HAS + -ed OR 3rd FORM.
When did you go to the movies?
Where have you been to?