Как все наверное знают отличить Present Perfect и Past simple…?

B: Then where have you been? (Present Perfect) A: Oh, nowhere. I wanted (Past simple) to go to America two years ago,but now i don't want to go there.B: Why? A: I understood (Past simple) that my wish is impossible, so i abandoned (Past simple) that idea. И 2-яB: Have you heard some interesting news? (Present Perfect) A: No.B: I heard (Past simple) that Brian flunked (Past simple) his exam last week. A: Why did (Past simple) he flunk the exam? B: He lost (Past simple) his homework, so he didn't repeat a topic. (Past simple)