Sometimes people with moderate-stage dementia find it easier to talk about themselves indirectly. It can feel unappealing or even threatening to be asked things directly, as in, "What do you think?" So when looking for insights or opinions from your loved one, try asking questions that are phrased about third parties. It may sound odd -- but it often yields the kind of information you're looking for.
Consider phrases like these:
"What did your mother used to do when. . . ?"
"When I was a girl, I thought [mention a topic you'd like to explore]. What about you?"
"What do you think [name of spouse] would have said about that?"
"If the dog could talk, I wonder what he'd be saying about this?"
"What do you suppose [name of spouse or another loved one] would have said about that?"
Obviously your comments need to suit the conversation, and not all people with moderate-stage dementia will be able to respond to these imagined conversations. But know that sometimes the most direct way into your loved one's mind is through a side door.