Look, I know that this is part of what you learn at journalism school.
"Mr. Politician, you said you were going to do X and you haven't done it yet. Can you comment?"
"Mr. Politician, what did you mean when you said you'd do X?"
I can tell you definitively on behalf of the general public, we do not need those answers from Donald Trump, thank you very much! It's perfectly OK not to ask those questions and remind him of some terrible thing he said he'd do.