Why apples and not an apple? Elma vs elmalar
Because elma is in the nominative, the sentence isn't talking about a specific apple, but about the fact that generally speaking, ducks eat apples.
The translation for "an apple", if I'm not mistaken, would be "Ördekler bir elma yer", to show that no specific apple, but only one, is meant instead.
so if it was "the ducks eat an apple" it will always have the word "bir" in front of it?
In English it is perfectly acceptable to say that the ducks eat apple just as it is possible to say that they eat chocolate.
Those are different. Chocolate as a substance is not countable. Apples are. We use normally use a plural on chocolate only when speaking of a box of chocolates and in that case we would say "the ducks eat chocolates" just as we say "the ducks eat apples".
I'm Canadian, a native English speaker and sometime teacher of English and in my more than 70 years I have NEVER come across a situation in which "The ducks eat apple" sounds natural. I would have counted it as an error had it turned up in a student's composition.
It may be acceptable in some regional dialects, but I suspect even there it would be rare. I would not expect a language learning program to include rare or local uses over standard everyday uses.
Türkçe öğrenmeye çalışaları zorlayacak bir durum; telafuz. Ben bile yavaş söylediğinde anlayabiliyorum bu kadını :D:D
I think you are right, but Turkish is ambiguous here. Both "ducks" and "The ducks" would be correct--one being a general statement and the other referring to a specific group of ducks. At least that's my understanding, but I hope a native speaker of Turkish would confirm.