Below is the text with the missing letters filled in and the nouns placed in the correct form:

For 1st declension nouns (like берёзка , окраина , рябина ), the ending is used in the Dative and Prepositional cases. For 2nd declension nouns (like воздух ), the ending -е is used in the Prepositional case. None of these words belong to the 3rd declension, which would require the ending -и . ✅ Final Answer

По (Dative) лепечут осинки. На берёзке (Prepositional) светятся золотые листочки. В воздухе (Prepositional) кружится тонкая паутина. На рябине (Prepositional) висят гроздья ягод. 1. Identify noun endings

The main task is to choose between the endings and -и . This depends on the declension (склонение) and the case (падеж) of the noun: Окраине : 1st declension, Dative case ( →right arrow ending -е . Берёзке : 1st declension, Prepositional case ( →right arrow ending -е . Воздухе : 2nd declension, Prepositional case ( →right arrow ending -е . Рябине : 1st declension, Prepositional case ( →right arrow ending -е . 2. Verify spelling rules