In the question: "Fais-tu la vaiselle" there is no question mark. I put "Do the dishes", which was marked wrong. The correct answer is supposed to be "Are you doing the dishes?" which is a question. I don't think I should be marked wrong here, because the example was not a question.
(Later)... OK, I have read more answers below, and it is clear now.
The command "Do the dishes" = Fais la vaiselle. (no pronoun).
The question " Are you doing the dishes?" = Fais-tu la vaiselle?