Questions & Answers about On oddycha powietrzem w parku i patrzy na drzewa.
Powietrzem is the instrumental case of powietrze (air).
Some verbs in Polish, including oddychać (to breathe), take the instrumental case to express “with / by means of what”:
- oddychać czym? – powietrzem (to breathe with air)
- pisać czym? – długopisem (to write with a pen)
- jechać czym? – autobusem (to go by bus)
Declension of powietrze (singular, most important forms):
- Nominative (who? what?): powietrze – air
- Instrumental (with what?): powietrzem – with/by air
So On oddycha powietrzem literally feels like “He breathes with air.”
W parku uses the locative case.
The preposition w (= in) normally takes the locative when it means “in/inside”:
- w domu – in the house
- w sklepie – in the shop
- w szkole – at school
- w parku – in the park
The noun park (masculine) in singular:
- Nominative: park – a/the park
- Locative (after w = “in”): w parku
So w park is ungrammatical; you must say .