plecaka

In a sentence

• Włożyłem książkę do plecaka.

  I put the book into the backpack.

  Here, 'plecaka' is the genitive singular form of 'plecak', used to indicate possession or relation to an object.

• Szukałem kluczy w plecaka, ale ich tam nie było.

  I was looking for the keys in the backpack, but they were not there.

  In this sentence, 'plecaka' is incorrectly used in place of 'plecaku', which should be in the locative singular form to indicate the location within something.

• Nie mogę znaleźć plecaka, który zostawiłem w parku.

  I can't find the backpack that I left in the park.

  Here, 'plecaka' is the accusative singular form of 'plecak', used as the direct object of the verb, indicating the backpack being the object of the action.