(Almost) everything you can say to Apple's virtual assistant. There's a lot you can do with Apple's virtual assistant -- and some things you can't do. For example, while Siri can send texts, search Twitter, and open up your front-facing camera, she can't adjust your device's ring volume (something OK Google can do). Complicating the matter, Siri doesn't work exactly the same way on a Mac as she does on iOS. Click here for the full story.