The present perfect is a present tense. It always tells us something about now. 'Tom has lost his key' = he doen't have his key now. The past simple tells us only about the past. 'Tom lost his key' = whe don't know whether he has it now or not. We only know that he lost it at some time in the past. Jack grew a beard but but now he has shaved it off. ( so he doesn't have a beard now ) They went o..