tage

In a sentence

• Ich habe seit drei Tagen nichts gegessen.

  I haven't eaten anything for three days.

  Here, 'Tagen' is the dative plural form of 'Tag', used after the preposition 'seit' to denote a time span in the dative case.

• Die Tage werden immer kürzer im Winter.

  The days are getting shorter in winter.

  Here, 'Tage' is the nominative plural form of 'Tag', functioning as the subject of the sentence referring to multiple days.

• An manchen Tagen scheint die Sonne besonders schön.

  On some days, the sun shines particularly beautifully.

  Here, 'Tagen' is the dative plural form of 'Tag', used with the preposition 'an' to indicate the specific days during which something occurs.