substitucions

In a sentence

• Les substitucions de mestres van ser anunciades al claustre.

  The teacher substitutions were announced at the faculty meeting.

  Here, 'substitucions' is used to mean the act of substituting one teacher for another in a professional setting.

• Aquest jugador fa moltes substitucions durant el partit.

  This player makes many substitutions during the game.

  In this context, 'substitucions' refers to exchanges or replacements of players during a sports event.

• He hagut de fer substitucions dels llibres antics per edicions noves.

  I had to substitute the old books with new editions.

  Here, 'substitucions' is used to describe replacing old objects (in this case, books) with new ones.