Form
to be (am, are, is) + infinitive + -ing

Examples
Affirmative sentences: I am playing football. You are playing football..
Negative sentences: I am not playing football. You are not playing football.
Questions: Am I playing football? Are you playing football?

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Present Progressive - Use

1) actions happening at the moment of speaking
Peter is reading a book now.
2) fixed plan in the near future
She is going to Basel on Saturday.
3) temporary actions
His father is working in Rome this month.
4) actions happening around the moment of speaking (longer actions)
My friend is preparing for his exams.
5) trends
More and more people are using their computers to listen to music.
6) repeated actions which are irritating to the speaker (with always, constantly, forever)
Andrew is always coming late.

Other Examples:

You are learning English now.
You are not swimming now.
Are you sleeping?
I am sitting.
I am not standing.
Is he sitting or standing?
They are reading their books.
They are not watching television.What are you doing?
Why aren't you doing your homework?

Text: On the telephone

Tracy: Hello, can I speak to Alex.
Alex: This is Alex, who is speaking?
Tracy: Hi, this is Tracy.
Alex: Hi Tracy. What are you doing?
Tracy: Oh, I'm just watching TV. What are you doing?
Alex: Well, I'm cooking dinner.
Tracy: What are you cooking?
Alex: I'm baking some potatoes, boiling some carrots and grilling a steak.
Tracy: It sounds delicious.
Alex: What are you doing for dinner tonight?
Tracy: Well, I don't have any plans...
Alex: Would you like to come over for dinner?
Tracy: Oh, I'd love to. Thanks.
Alex: Great. Mary and Jack are also coming. They are arriving at seven.
Tracy: OK, I'll be there at seven, too.
Alex: OK, see you then. Bye.
Tracy: Bye.

QUIZ -
click here: http://www.eflnet.com/grammar/presprog.php

Read more: http://www.englisch-hilfen.de/en/grammar/pres_pro.htm
http://www.englishpage.com/verbpage/presentcontinuous.html
http://www.englishclub.com/grammar/verb-tenses_present-continuous.htm
http://web2.uvcs.uvic.ca/elc/studyzone/330/grammar/pcont.htm