1. Subject + Have/has + verb ( past participle ) …
Present Perfect Tense
The sentence pattern for present perfect tense
Subject + Have/has + verb ( past participle ) …
For example:
1 – I’ve read that book before.
2 – She’s already done her homework.
3 - They have lived in Jeddah for ten years.
4 - He has worked there.

2. There are 4 primary reasons to use the Present Perfect Tense.
To talk about a completed past action at a non-specific time. The action is finished. You don’t know, care or remember when it happened. The action can continue to the present or to the future.
For example:
1 – I’ve read that book before.
2 – She’s already done her homework.
3 - They have lived in Jeddah for ten years.

3. ever and never are common with this use:
Reason #2
Use present perfect to express an experience as part of someone’s life.
For example:
1 – I’ve travelled a lot in Africa.
2 – He’s lived all over the world.
ever and never are common with this use:
1 – Have you ever been in a car crash?
2 – My mother has never flown in a plane.

4. Reason #3
Action that started in the past and has continued until now. Often used with since (indicating the beginning of action) or for (indicating the duration of action):
For example:
1 – I’ve studied at this school since last June.
2 – She’s lived in West Palm Beach for 2 months.
3 - Fahad and Omar have known each other since they were at primary school.

5. Reason #4
use the present perfect to express past action with results in the present ( immediate past ).
The adverbs just , already and yet are common used. Yet is used in questions and negatives.
Example:
1) The taxi’s arrived.
2) I’ve lost my wallet.
3) He has just taken the medicine.
4) Has she got-up yet?
5) It’s 11 o’clock and she hasn’t got up yet.
6) I’ve already eaten breakfast.

6. The form of the present perfect simple tense:
Subject + Have (in the simple present) + Verb (in the past participle form)
+ Positive
- Negative
? Question
I have worked there.
He has worked there.
We have worked there.
I have not worked there.
He has not worked there.
We have not worked there.
Have you worked there?
Has he worked there?
Have we worked there?

7. Present perfect vs past simple tense:
The use of past simple instead of present perfect requires clear reference to a past period/moment:
Present perfect
Simple past
I have met that girl before
I met that girl at the beach last Saturday.
Have you seen Nancy recently?
Did you see Nancy yesterday?
We have discussed this issue a few times.
We discussed this issue last month.
I have had some tests this week.
I had some tests last week.