квартиры

In a sentence

• Я иду в квартиру, которая находится на первом этаже.

  I am going to the apartment that is located on the first floor.

  Here, 'квартиру' is the accusative case of 'квартира', indicating motion to a specific apartment.

• Квартиры в этом районе очень дорогие.

  The apartments in this area are very expensive.

  In this sentence, 'квартиры' refers to the plural form, indicating multiple apartments.

• Ключ лежит на полке возле квартиры.

  The key is on the shelf near the apartment.

  Here, 'квартиры' is in the genitive case, showing possession or proximity.