I dug up the study by Stone Temple to see what kind of questions were asked (eg: are the questions really trivial or not) and they provide a few exampled in their write up. I am actually seriously impressed by how well those "personal assistants" work compared to what I would expect. Kudos to the engineers who built those things!

(Disclosure: I never worked on any of those, nor do I work for any of the companies making them)