A) Used to refer to past events without determining the time at which occurred.
- Ex:He estado en América.
- I have been to America
B) Used to express unfinished situations.
- Ex: Todavía no he leído ese libro que me recomendaste.
- I have not read that book you recommended to me yet.
C) Used to express an action that started in the past and still has consequences in the present moment.
- Ex: Ha escrito sólo un libro pero se ha ganado la fama.
- She has written only one book but she has made a name for herself.
She wrote the book in the past, the book is complete and published, but the consequences of writing that book are still present now as she still enjoys of her fame.
D) Used to refer to past actions or situations in a period of time that includes the actual moment it happens or a moment very close to the time of the event.
- Ex: Hoy no he podido ir a clase de español.
- Today i could not to go to spanish class.