Present Perfect

In English class we have been learning and practicing the present perfect tense.  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, just, etc.

We use just to explain something that has recently happened.  Already is for an affirmative sentence and yet is for a negative sentence! Remember the placement of already and yet in a sentence!
Check this site to know more and do the exercises. It´s a good practice for the English exam

Practice your present perfect for recent actions using already, just, and yet:
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Website with lots of practice!
The present perfect tense explained and extra practice here!