Stary odkurzacz stoi w garażu, ale nowego używamy codziennie.

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Breakdown of Stary odkurzacz stoi w garażu, ale nowego używamy codziennie.

• nowy: new
• codziennie: every day
• ale: but

Questions & Answers about Stary odkurzacz stoi w garażu, ale nowego używamy codziennie.

Why does garaż change to garażu in w garażu?

Because of case and the preposition w.

• The basic (dictionary) form is garaż (nominative).
• After w meaning “in” (location, not movement), Polish normally uses the locative case.
• The locative singular of garaż is garażu.

So:

• Samochód jest w garażu. – The car is in the garage. (locative)
• Wchodzę do garażu. – I go into the garage. (here do also triggers genitive: garażu)

You would only use a different case with w if you were talking about movement into something (then it takes the accusative), e.g.:

• Wchodzę w garaż – I walk into the garage (much less common than do garażu, but shows the pattern).

In your sentence, nothing is moving; it’s just located there, so w garażu (locative) is correct.

Why do we say just nowego in the second part and not repeat odkurzacza?

Polish, like English, can omit a repeated noun if it is obvious from context, and leave only the adjective, which then means “the new one”.

The full sentence could be:

• Stary odkurzacz stoi w garażu, ale nowego odkurzacza używamy codziennie.

Because has already appeared, it’s natural to shorten it to: