Thanks, what about the other question?
I'm not in a position to listen to the recording right now. As Dormouse says, the usage is very context-dependent and native use does differ. For instance, I remember eavesdropping on a conversation once which contained the line:
"Did you see him today?"
From the context, it was clear that this was simply a neutral inquiry. But I wouldn't have phrased it that way. The simple past has a distancing effect, implying that the time for seeing him today is somehow over. So this really only makes sense to me if an appointment is involved. Otherwise, I would ask, "Have you seen him today?"
With, "Did you eat today?" vs "Have you eaten today?" the situation is somewhat reversed. An appointment is assumed (since most people in our society eat three times a day), so simple past feels less marked to me. Pragmatically, "Have you eaten?" is more likely to function as an invitation--but again, for many American English-speakers, this distinction is weak if observed at all.
"Richmond is a real scholar; Owen just learns languages because he can't bear not to know what other people are saying."--Margaret Lattimore on her two sons