"Do you begin?"
I imagine it's a shared Germanic language trait. English also marks yes-no questions by putting the verb first.
"You are tired." "Are you tired?"
"He can play the piano." "Can he play the piano?"
With many verbs, questions need a helping "do", but then that verb goes at the beginning as well:
"Paul eats too much." "Does Paul eat too much?"
To the best of my knowledge (which isn't much), English is the only language that has this "do" tense, a tense that appears to be optional and yet overused at the same time in the "declarative," but absolutely mandatory in the "interrogative."
Correct me if I'm wrong, but one can say, "Eats Paul too much?" - but this has become replaced with the "do" form of the question - so much so that it doesn't sound right to anyone these days.
Unless they're reading the Bible.
When to put the verb at the front
When it's a yes-no question or a command.
Like in English, basically.
"Do you begin?" (verb "do" at the beginning of a yes-no question)
"Are you sure?" (verb "are" at the beginning of a yes-no question)
"Don't be afraid!" (verb "do" at the beginning of a command)
"Look at me!" (verb "look" at the beginning of a comamnd)
My apologies. What I had meant is what you presented. My concern is that Duo has avoided separable prefix verbs like the plague, along with having never presented a lesson on them. It's why many newcomers get some really strange answers wrong - what appears in German as a preposition left at the end of the sentence was, in fact, the separated prefix of a completely different verb than what they thought they read.
As for me, "anfangen" would have been the preferred verb in that sentence, but it wasn't offered as a choice in the word box version of the question.
Of course not. "Du ihr beginnt" does not make any sense.
"you" can be "du", "ihr" or "Sie". So "Do you begin" can be
"Beginnt ihr?" or
Yes/no questions are formed by inversion (verb first) in German. There is no circumscription using "to do" like in English. "do" and "du" sound alike, but have nothing to do with one another.
Why does DL German group does not accept this correct answer?
Because it is not correct.
"du" takes "beginnst" as its verb form. Saying "beginnt du" is like saying "does you begin?".
It is you who is annoying, when you refuse to learn and instead repeat your faulty answer several times.