1. He asked  them which book or books they were reading at that moment. 
2. He asked  them where their favourite place to read was.
3. He asked  them who their  favourite poet was.
4. He asked  them who their  favorite character was.
5. He asked  them to name three desert island choices.
6. He asked  them what their  favorite children's books were.
7. He asked  them what book they would like to be filmed. 
8. He asked  them which book changed their  life.
9. He asked them which book they  thought was good reading for everyone.