Respuestas

2013-06-17T15:54:41+02:00
We use the Present Perfect to say that an action happened at an unspecified time before now. The exact time is not important. You CANNOT use the Present Perfect with specific time expressions such as: yesterday, one year ago, last week, when I was a child, when I lived in Japan, at that moment, that day, one day, etc. We CAN use the Present Perfect with unspecific expressions such as: ever, never, once, many times, several times, before, so far, already, yet, etc.

Ejemplos 
I have been to France.
This sentence means that you have had the experience of being in France. Maybe you have been there once, or several times.I have been to France three times.
You can add the number of times at the end of the sentence.I have never been to France.
This sentence means that you have not had the experience of going to France.I think I have seen that movie before.He has never traveled by train.Joan has studied two foreign languages.A: Have you ever met him?
B: No, I have not met him.
¡La mejor respuesta!
2013-06-17T20:46:34+02:00
Es bien simple! 
Uso
El presente perfecto nos sirve para oraciones que se efectuaron en un tiempo pasado que no es especifico, y tampoco importa que lo sea
¿Como formar oraciones?
Afirmativo 
Sujeto + auxiliar verbo (puede ser Have o Has, dependiendo del sujeto) + Verbo acción en pasado participio  + complemento
♥ Negativo
Sujeto + verbo auxiliar + partícula Not + Verbo acción en participio+ complemento
♥ Interrogativo
Verbo auxiliar + sujeto + Verbo acción en participio + complemento

♫ Ejemplos♫ 

Afirmativo 
I have played xbox
Negativo
I have not (o I haven't, como prefieras) played xbox
Interrogativo
Have I played xbox?
Respuesta corta
Yes/No, I have/haven't

¡Mucha suerte!