1) actions happening at the moment of speaking
Peter is reading a book now.
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2) fixed plan in the near future
She is going to Basel on Saturday.
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3) temporary actions
His father is working in Rome this month.
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4) actions happening around the moment of speaking (longer actions)
My friend is preparing for his exams.
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5) trends
More and more people are using their computers to listen to music.
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6) repeated actions which are irritating to the speaker (with always, constantly, forever)
Andrew is always coming late.
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Signal words
now, at the moment, Look! Listen!
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Form
to be (am, are, is) + infinitive + -ing
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Examples
Affirmative sentences:
I am playing football.
I'm playing football. You are playing football.
You're playing football.
Negative sentences:
I am not playing football.
I'm not playing football. You are not playing football.
You're not playing football.
You aren't playing football