No question corresponds to the vocative case. This is used in calling somebody, and has no connection with the sentence. It is inserted in the sentence and separated from it by a comma.
The Use of the Individual Cases.
The nominative is the case of the subject of a sentence.
The objective (or accusative) is the case of the direct object of a positive, transitive verb. (Transitive verbs express action which is transferred upon something. Ex. to see some one, to have something etc. are transitive verbs.)
(Intransitive verb: to go, jíti).
Negative transitive verbs require their object in the possessive case. Vidím matku. I see mother. But: Nevidím matky. Nemáme dělníků. However in modern colloquial Bohemian this use of the possessive is being replaced by the objective.
Possessive (or genitive) is used as the English possessive. (In Bohemian the possessive comes after the name of the possessed object. Mother’s child. Dítě matky.) The possessive is further used:
b) to express the object of the negative transitive verb.
c) to denote parts and quantities, libra kávy, sklenice vody.
d) after numerals higher than four, after indefinite numerals trochu, několik etc. několik hochů, trochu vody.