πατέρα

In a sentence

• Ο πατέρας μου είναι γιατρός.

  My father is a doctor.

  Here, 'πατέρα' is used in the nominative case as the subject of the sentence, indicating a direct identification of relation.

• Χρειάζομαι τον πατέρα μου τώρα.

  I need my father now.

  'Πατέρα' is used in the accusative case as the object of the verb 'χρειάζομαι', representing the person being referred to.

• Μίλησα για τον πατέρα στους φίλους μου.

  I talked about my father to my friends.

  In this instance, 'πατέρα' is also in the accusative case, used within a prepositional phrase introduced by 'για', indicating the discussed topic.