We use the present perfect when we want to look back from the present to the past.

We can use it to look back on the recent past.

I've broken my watch so I don't know what time it is.
They have cancelled the meeting.
She's taken my copy. I don't have one.
The sales team has doubled its turnover.

When we look back on the recent past, we often use the words 'just' 'already' or the word 'yet' (in negatives and questions only).

We've already talked about that.
She hasn't arrived yet.
I've just done it.
They've already met.
They don't know yet.
Have you spoken to him yet?
Have they got back to you yet?

It can also be used to look back on the more distant past.

We've been to Singapore a lot over the last few years.
She's done this type of project many times before.
We've mentioned it to them on several occasions over the last six months.
They've often talked about it in the past.

When we look back on the more distant past, we often use the words 'ever' (in questions) and 'never'.

Have you ever been to Argentina?
Has he ever talked to you about the problem?
I've never met Jim and Sally.
We've never considered investing in Mexico.

How do we make the Present Perfect Tense?

The structure of the present perfect tense is:

subject	+	auxiliary verb	+	main verb
		have		past participle

Here are some examples of the present perfect tense:

	subject	auxiliary verb		main verb
+	I	have		seen	ET.
+	You	have		eaten	mine.
-	She	has	not	been	to Rome.
-	We	have	not	played	football.
?	Have	you		finished?
?	Have	they		done	it?

How do we use the Present Perfect Tense?

This tense is called the present perfect tense. There is always a connection with the past and with the present. There are basically three uses for the present perfect tense:

experience
change
continuing situation

1. Present perfect tense for experience

We often use the present perfect tense to talk about experience from the past. We are not interested in when you did something. We only want to know if you did it:

I have seen ET.
He has lived in Bangkok.
Have you been there?
We have never eaten caviar.

past

present

future

!!!

The action or state was in the past.

In my head, I have a memory now.

Connection with past: the event was in the past.
Connection with present: in my head, now, I have a memory of the event; I know something about the event; I have experience of it.

2. Present perfect tense for change

We also use the present perfect tense to talk about a change or new information:

I have bought a car.
past	present	future
-	+
Last week I didn't have a car.	Now I have a car.

John has broken his leg.
past	present	future
+	-
Yesterday John had a good leg.	Now he has a bad leg.

Has the price gone up?
past	present	future
+	-
Was the price $1.50 yesterday?	Is the price $1.70 today?

The police have arrested the killer.
past	present	future
-	+
Yesterday the killer was free.	Now he is in prison.

Connection with past: the past is the opposite of the present.
Connection with present: the present is the opposite of the past.

3. Present perfect tense for continuing situation

We often use the present perfect tense to talk about a continuing situation. This is a state that started in the past and continues in the present (and will probably continue into the future). This is a state (not an action). We usually use for or since with this structure.

I have worked here since June.
He has been ill for 2 days.
How long have you known Tara?

past

present

future

The situation started in the past.

It continues up to now.

(It will probably continue into the future.)

Connection with past: the situation started in the past.
Connection with present: the situation continues in the present.

For & Since with Present Perfect Tense

We often use for and since with the present perfect tense.

We use for to talk about a period of time - 5 minutes, 2 weeks, 6 years.
We use since to talk about a point in past time - 9 o'clock, 1st January, Monday.

for	since
a period of time	a point in past time
	x------------
20 minutes	6.15pm
three days	Monday
6 months	January
4 years	1994
2 centuries	1800
a long time	I left school
ever	the beginning of time
etc	etc