Imagine if you will ,  that we have a system that does all that understanding that we want it to do based on utterances.
Mm - hmm.
It should be possible to make that system produce questions. So if you have the knowledge of how to interpret " where is X ? " under given conditions , situational , user , discourse and ontological  conditions , you should also be able to make that same system ask " where is X ? "
Mm - hmm.