I put "Was ist du?" ("what is you" Lol, I knew that couldn't be right but it was what I heard!) Duo marked my answer correct! Is this a glitch? Or is "Was ist du?" really a legit sentence?
Same here. Maybe there were complaints about hearing a difference between ist/isst, and afterall, "What are you?" is a valid question.
Actually, 'what are you' would have to be typed as 'Was bist du?' 'Ist' wouldn't make any sense.
Was ist du isn't a legit sentence because it would be Was bist du (conjugations haha)
"Was ist Du" is not correct. I assume that Duolinge has problems differentiating between s, ss, and ß. This is like a software issue more than a language issue.
Edit: 'Was bist du?' is a legit sentence I think.
I have a possible example.
Think Halloween Eve and a bunch of kids come trick or treating at your door. So you ask each of them what they are dressed up as:
"Ahh, sehr gut! Und was bist du?"
This would be "Ahh, sehr gut! was (or wer) bist du?"; which is, as others mentioned already "Ahh..., what (who) are you?" :)
Maybe I can help: The problem is that when you hear the sentence for people learning German it can be either "was ist du" or "was isst du"
You can forget about the first one "was ist du?" because the sentence does not make any sense and therefore no one will use it.
That leaves the the second version: "Was isst du?"; it comes from the German verb "essen"="to eat" and means "what do you eat?" (using all personal pronouns subject case you get: was esse ich , was isst du, was isst er/sie/es, was essen wir, was esst ihr, was essen sie).
Looking at the sentences just presented you can see that the only sentences that might present a problem are 2nd person singular and third person singular. But knowing how they are spelled and know what they can mean they should provide no problem.
Hope that helps you. :-) Enjoy