Present Perfect

This tense is called [present] perfect because we can see (now, in the present) the result of what has been perfected, done, carried out, achieved.
I have written a letter and here it is, all done and ready for the post.
He used to be ἄοκνος energetic but now he will not lift a finger:
    ῥᾴθυμος [ἀργὸς] γέγονε 
The sun has gone done, so it is evening now
   ἑσπέρα γέγονε 
Compare with: What happened (simple fact, stress on 'past event'). Tell me!
   εἰπέ μοι τί ἐγένετο 
Remember the perfect endings for  πέπωκα: I've drunk and my thirst is therefore quenched .