Y: Diana can tell you when the party will be held.
X: Whom did they invite to the party?
Y: You will have to ask Diana whom they invited.
X: Where did Diana go?
Y: I have no idea where she went.
X: Where will she be this afternoon?
Y: She didn't tell me where she would be.
X: When did she return?
Y: I beg your pardon.
X: Please tell me when Diana returned?
Y: Sorry. I can't tell you.