PRESENT PERFECT

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Present Perfect is one of the most difficult constructions for brazilians to understand.
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There are some facts to be considered before using this construction:
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1. Situation started and goes on
- I have worked for this company since 1999.
- Julia hasn't seen her father for a week.

2. Past situation without time reference
- Mark has been to Europe twice.
- We've bought a new car.

3. Recent Information
- My parents have just arrived from Australia.
- He's finished the article.

4. PRESENT PERFECT CONTINUOUS: constant or repeated action:
- Won't you get some rest? You've been playing this game for hours!
- Sue's been taking English classes since last month.

*****The only way to perfection is through practice.

Click on the links below:
http://www.better-english.com/grammar/pspp1.htm
http://www.smic.be/smic5022/testtenses2.htm
http://www.smic.be/smic5022/presentperfect2.htm
http://www.geocities.com/gob72/grammarverbtenses.html
http://www.geocities.com/gob72/presentvspresentperfect.htm

Hope it will help you improve your English!
Best wishes,
André