I'm currently working on getting Zavier to ask "What is it?"
First, I wrote "What is it?" on a cue card, and then I had him read it at appropriate times. Once he got the hang of the concept, I put the cue card away.
Now I hold something hidden in my hand, and prompt him by saying, "Wuh."
Me: "Zavier, look. Wuh..."
Zavier: "What is it?"
Me: (opening my hand) "It's a rock."
Zavier: "It's a rock!" (smiles)
We've been working on it for a few days. I'm hopeful that by the end of the month, he'll start to ask the question unprompted, and possibly even spontaneously in various settings.