Two gods, truth and false. Self explanatory here, one always tells the truth, one always lies.
You have one question that can only be answered with yes or no, but here's the catch:
They only answer with ja or da. You don't know which means yes and which means no. They will not answer with anything BUT ja or da.
You much determine which is which.
This is of my own partial design. My original edit had two questions, but as I thought of it more, I realized I could solve it in one. Good luck.
Ghostly, she stood in front of him and looked into his eyes. "I am here," she said. "I am here. I want to touch you." She pleaded: "Look at me!" But he would not see her; he only knew how to look at the outside of things.