Present simple, continuous, perfect.

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Present Simple
We use the present simple to talk about actions we see as long term or permanent. It is a very common and very important tense.

Here, we are talking about regular actions or events.

They drive to the office every day.
She doesn't come here very often.
The news usually starts at 6.00 every evening.
Do you usually have bacon and eggs for breakfast?
Here, we are talking about facts.

We have two children.
Water freezes at 0° C or 32° F.
What does this expression mean?
The Thames flows through London.
Here, we are talking about future facts, usually found in a timetable or a chart.

Christmas Day falls on a Monday this year.
The plane leaves at 5.00 tomorrow morning.
Ramadan doesn't start for another 3 weeks.
Does the class begin at 10 or 11 this week?
Here, we are talking about our thoughts and feelings at the time of speaking. Although these feelings can be short-term, we use the present simple and not the present continuous.

They don't ever agree with us.
I think you are right.
She doesn't want you to do it.
Do you understand what I am trying to say.

Present Continuous
The present continuous is used to talk about present situations which we see as short-term or temporary. We use the present simple to talk about present situations which we see as long-term or permanent.

In these examples, the action is taking place at the time of speaking.

It's raining.
Who is Kate talking to on the phone?
Look, somebody is trying to steal that man's wallet.
I'm not looking. My eyes are closed tightly.
In these examples, the action is true at the present time but we don't think it will be true in the long term.

I'm looking for a new apartment.
He's thinking about leaving his job.
They're considering making an appeal against the judgment.
Are you getting enough sleep?
In these examples, the action is at a definite point in the future and it has already been arranged.

I'm meeting her at 6.30.
They aren't arriving until Tuesday.
We are having a special dinner at a top restaurant for all the senior managers.
Isn't he coming to the dinner?

Present Perfect
(Please note that British and American English have different rules for the use of this tense. The explanation and exercises here refer to British English. In American English, it is often acceptable to use the past simple in some of these examples.)

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.