Learn Hardcore Polish: Powinieneś ćwiczyć w siłowni, jeśli na dworze jest zima. - You should exercise in the gym if it is winter outside.

powinieneś is the second-person singular masculine conditional form of the modal verb powinien, translating as “you should.” In Polish the conditional mood is built from the past-tense stem plus the particle by and a personal ending. Here:

past stem: powinien-
conditional particle + ending: -eś (fusion of by + ś)
So powinien + by + ś → powinieneś, expressing obligation or advice.

Why is ćwiczyć in the infinitive form?

Modal verbs like powinieneś require that the main verb stay in the infinitive. You don’t conjugate ćwiczyć (to exercise); powinieneś already carries all the person and tense information.

What case is used in w siłowni, and why?

The preposition w (“in”) when indicating a static location takes the locative case, which answers “gdzie?” (“where?”). The noun siłownia (gym) becomes siłowni in locative, so w siłowni = “in the gym.”

Why is it na dworze instead of na dwór, and how does it differ from na zewnątrz?

na + dworze (locative) means “outside” (in a location).
na + dwór (accusative) would imply movement “onto the yard.”
Meanwhile, na zewnątrz also means “outside,” but is more formal or general. na dworze is colloquial and typically refers to being outdoors at or near a specific place.

Why do we say jest zima to mean “it’s winter”?

zima is a feminine singular noun. Polish doesn’t use a separate “it” pronoun here—just the third-person singular of być (“to be”), which is jest, plus the noun. So jest zima literally means “is winter” but functions as “it’s winter.”

Why is there a comma before jeśli?

In Polish, subordinate clauses introduced by conjunctions like jeśli (if) are always separated from the main clause by a comma. Here jeśli na dworze jest zima is a conditional adverbial clause, so it’s preceded by a comma.

What’s the difference between jeśli, gdy, kiedy, and gdyby?

jeśli / jeżeli = if (real or possible condition)
gdy / kiedy = when (temporal); gdy can sometimes mean if in colloquial speech when referring to real events
gdyby = if in unreal or hypothetical (contrary-to-fact) conditions
In our sentence we use jeśli, because it introduces a real/possible condition (if it’s winter).

How would you change powinieneś if you’re talking to a female or to a group?

Polish conditional forms agree in gender and number:

to a female: powinnaś ćwiczyć
to a mixed/masculine group: powinniście ćwiczyć
to a feminine group: powinnyście ćwiczyć

Why isn’t the subject pronoun ty included in powinieneś ćwiczyć?

Subject pronouns are optional in Polish because the verb ending already indicates person and number. You could say Ty powinieneś ćwiczyć, but it’s redundant and usually omitted unless you want extra emphasis.