"Mom, why are you wearing my shoes?"
Translation:Mamá, ¿por qué usas mis zapatos?
Tus is a possessive plural for your: tus zapatos - your shoes, the possessive here is mis - my shoes.
What you're translating here is essentially 'you wearing', so it's the conjugated form of usar - to use:
Usted usa or tú usas.
...usas mis zapatos - you are wearing my shoes, or you wear my shoes.
I wrote Mamá, ¿por qué tú usas mis zapatos? but DL said it’s wrong because the right answer is Mamá, ¿por qué usas mis zapatos?. Can anybody explain WHY my answer should be wrong, since YOU is expressed in English? Should I guess when DL wants the pronoun and when it doesn’t?