Translation:¿Cuándo hiciste eso?
Why is "Cuándo lo hiciste" wrong? I hate it when I lose my last heart at the 15th question because of something like this -.-
That would be, "When did you do it" rather than "that." There's no clitic equivalent for "this" or "that."
why is 'cuando lo hizo eso' wrong?
lo and eso are redundant
Hicieron is the USTEDES version, which is the formal PLURAL version of you. Meaning that Usted means "you", but Ustedes means "you all"! Therefore, " ¿Cuándo hicieron eso?" should not be counted as a possible correct solution.
Was "has hecho" a trick, since the sentence should have then read "When have you done that?"? Would not only "hiciste" and "hicieron" be the only options? How does this system work, anyway?
Cuando lo hiciste?
Why isn't this right: ¿Cuándo usted hizo eso?
I know pronouns are optional, but including usted here is wrong?
¿Cuándo hizo usted eso? is the right order formulating a question :)
Why was "Cuándo tu hiciste eso?" wrong?
Since it's a question, the verb comes before the pronoun.
You don't need tú and tu is your. Word order if you did include tú likely played a part.
I put tú (with accent) in this sentence and was wrong
Shouldn't Cuándo hacías eso work as well?
How about: Cuándo hacían eso. Is this wrong?