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?
Here are some grammar exercises. Please note that these are different from the one available in English Grammar Secrets.