"Dych chi wedi ymolchi eto?"

Translation: Have you washed yet?

[XamonasChe]

"Did you wash yet?" Is wrong. I don't see why.

[ibisc]

Possibly the difference between the usual British English 'have you...?' and the American English 'did you...?'

[jekyllhj7]

True it is the difference between British English (probably the people who developed this) and American English. After being corrected I can see that "have you washed" makes sense, but it is not what comes to mind when translating - especially when I'm doing a timed practice.
Most Americans just don't use that type of phrasing.
I've requested that it should be marked as correct.

[RowenaJane]

You have to translate as 'have you' because it is the perfect tense.

[Cynphony]

I'm thrown by "eto"
It was "yet" and later "again"
Is there only the one word for both? I left off the word "again" because there was no "yet" as a choice.

[ibisc]

eto is commonly used to mean both 'again' and 'yet'.

[silverlight513]

How come "have you washed up again" was marked as incorrect?

[ibisc]

ymolchi = 'to wash oneself' or 'to get washed'

So the most straightforward translation is 'Have you washed yet?'