तक

In a sentence

• मैं अपने स्कूल तक पैदल जाता हूँ।

  I walk to my school.

  Here, 'तक' is used as a postposition indicating a limit or destination.

• कल रात मैं किताब पढ़ता रहा, सुबह तक।

  Last night, I kept reading a book until morning.

  Here, 'तक' is used as a postposition indicating a duration or endpoint in time.

• इस समस्या का समाधान खोजने तक हम रुकेंगे नहीं।

  We will not stop until we find a solution to this problem.

  Here, 'तक' is used to imply a condition or state persisting up to a point.