Here’s the completed dialogue with the correct forms:
Editor: Where's Stevens? I haven't seen him for days.
Secretary: He has gone to LA to interview Brad Pitt.
Editor: How long has he been in LA?
Secretary: Three days.
Editor: What about Milton and Knowles?
Secretary: They have gone to London. They're going to interview Keira Knightley.
Editor: Has anyone been to Spain to talk to Penelope Cruz?
Secretary: Smith has been to her country house. He interviewed her there yesterday, and he is coming back today.
