"Why did they come to the previous lecture?"
Translation:Önceki derse neden geldiler?
I don't understand, why it is "geldiler" and not "geldiler mi" that is the question form of the verb. I am thinking that the question word "neden" absorbs the question form of the verb, but I would like to know if this assumption is correct. Also, can we put "neden" in the beginning of the sentence, such as ''neden önceki derse geldiler?''
"Why did they come to the previous lecture?" Translation: Önceki derse neden geldiler?
''Neden önceki derse geldiler?'' - Correct other answer. Part 1
"Why did they come to the previous lecture?" - This has already happened (past tense) & is being questioned.
Önceki derse neden geldiler mi? - Evet - yes. The question particle can be used here - mi?
Önce - before & previous (adjective) & (adverb) Önceki - the previous. Part 2
You are correct & let's wait & see for any comments. I wish I could offer more evidence for part 2.