He's done what I used to be always watching out against: he's disappeared.
He's done what I told him to do, and it's ME he wants.
You know already that I've done what I could to look after things for you while you've been ill?
It's going to last till I've done what I aimed at doing when I started!
The above list will hopefully provide you with a few useful examples demonstrating the appropriate usage of "done what" in a variety of sentences. We hope that you will now be able to make sentences using this group of words.