Learn Polish: Dobra gleba daje roślinom nie tylko wodę, lecz także tlen. - Good soil provides plants not only with water, but also with oxygen.

Dobra gleba daje roślinom nie tylko wodę, lecz także tlen.

Good soil provides plants not only with water, but also with oxygen.

Breakdown of Dobra gleba daje roślinom nie tylko wodę, lecz także tlen.

to give (imperfective)

Questions & Answers about Dobra gleba daje roślinom nie tylko wodę, lecz także tlen.

How rigid is the pairing of nie tylko and lecz także? Can I use ale instead of lecz?

You can absolutely use ale. In fact, nie tylko ..., ale także ... (or ale też) is more common in everyday speech. Lecz means the exact same thing but sounds slightly more formal or written.

Do the nouns following nie tylko and lecz także always share the same case?

Yes, almost always. The conjunction connects two parallel ideas that share the exact same grammatical role in the sentence. Here, both wodę and tlen are direct objects being "given" by the soil, so they must both be in the accusative case as demanded by the verb daje.

Why is it roślinom here instead of the basic plural rośliny?

Roślinom is the dative plural form of roślina (plant). The verb dawać (to give) requires the dative case for the receiver, or the indirect object. The soil is giving water and oxygen to the plants.

Since wodę and tlen are both in the accusative case here, why does only wodę change its ending from the dictionary form?