"How many sheep does the child see?"
Translation:Kiom da ŝafoj vidas la infano?
It's because of da which doesn't accept accusative. La infano vidaj ŝafojN. La infano vidas multajN ŝafojN. La infano vidas multe da ŝafoj.
It's a pity. For example: "Kiom da sxafoj vidas multe da infanoj" - Who sees whom?
That's a great point--nice example! It works out, though, because it's pretty rare to have the subject and the object have the form adverb+da+noun. And even then, context almost always makes it clear what the intended meaning is.
If you were really worried about getting your point across, you could say Kiom da ŝafoj vidas multaj infanoj or Kiom da ŝafoj vidas multajn infanojn, in which case the case-marking would come to the rescue.
No. Even though kiom da ŝafoj as a whole is the direct object, the noun ŝafoj is the object of the preposition da, which never assigns the accusative. And kiom is never marked for case.
How would the sentence be different if it were "How many sheep see the child?"
It would be Kiom da ŝafoj vidas la infanon, because infanon would be the direct object.
Yes, in the sentence Kiom da ŝafoj vidas la infanon, 'How many sheep see the child', the da is part of the subject, so it has no effect on other parts of the sentence. The noun phrase right after da can never be accusative, but other than this very locally determined rule, everything works as normal.
You could say "Kiom da ŝafoj estas la infano vidanta" ([…] is the child seeing), but you can't have 2 conjugated verbs (-as and -as in this case) in the same proposition.
I don't understand, I'm reading it as "How many sheep are seeing the child?", why is vidas before child if the child is seeing the sheep?