text: Adam: Mary, could you please cover for me today?
  Mary: Sorry, can't do, I'm stuck at home, Gill has a flu. Maybe Joe?
  Joe: Uhm, ok, tell the PM I said it's fine.
  Adam: I owe you one, really, thanks!
target: Mary can't cover for Adam because she is stuck at home with Gill, who has a flu. Joe will cover for Adam.