Czy ufasz swojej współlokatorce, kiedy zostawiasz jej klucze?

Czy is a yes/no question particle. It does not translate neatly into one English word; it simply signals that the sentence is a question.

So:

• Ufasz swojej współlokatorce... = You trust your roommate...
• Czy ufasz swojej współlokatorce...? = Do you trust your roommate...?

In everyday speech, Polish speakers sometimes omit czy if the intonation already makes it clear that it is a question.

Ufasz is the 2nd person singular form of ufać (to trust), so it already means you trust.

Polish often leaves out subject pronouns when the verb ending makes the subject clear.

• ufam = I trust
• ufasz = you trust
• ufa = he/she/it trusts

So there is no need to say ty here. You could say Czy ty ufasz... for emphasis, but normally it is omitted.

Because ufać takes the dative case, not the accusative.

The basic dictionary form is:

• współlokatorka = female roommate / flatmate

After ufać, it changes to the dative singular:

• ufać współlokatorce = to trust a female roommate

So:

• współlokatorka = nominative
• współlokatorce = dative

This is one of the key things to remember with ufać: you do not trust someone in the accusative; you trust someone in the dative.

Because swój / swoją / swojej is the reflexive possessive adjective, used when the possessor is the same as the subject.

Here, the hidden subject is you, and the roommate is your own roommate, so Polish naturally uses swojej:

• Czy ufasz swojej współlokatorce...? = Do you trust your (own) roommate...?

Using twojej is not always impossible, but swojej is the normal, idiomatic choice when the possession refers back to the subject.

A useful rule:

• use swój when something belongs to the subject of the sentence

Swojej is also in the dative singular feminine, because it agrees with współlokatorce.

So both words match:

• swojej współlokatorce

That means:

• feminine
• singular
• dative

This agreement is very important in Polish adjective + noun phrases.

Współlokatorka means a female roommate / flatmate / housemate, depending on context.

It is built from:

• współ- = co-, shared, fellow-
• lokatorka = female tenant / female lodger / female occupant

The masculine form is:

• współlokator = male roommate

So this sentence specifically refers to a female roommate.

Here, jej means to her.

It is the dative form of the pronoun ona (she), and it goes with zostawiasz:

• zostawiasz jej klucze = you leave her the keys

So the structure is:

• jej = indirect object, to her
• klucze = direct object, the keys

Yes, and that is something learners often notice.

Jej can mean either:

• to her (dative pronoun), or
• her (possessive)

So in isolation, jej klucze could mean:

• her keys, or
• the keys for her / to her, depending on context

In this sentence, the intended meaning is you leave her the keys. The context and the verb structure make that reading natural.

If you wanted to make it extra clear, you could say:

• zostawiasz jej swoje klucze = you leave her your keys
• zostawiasz klucze u niej = you leave the keys with her / at her place

Klucze is the accusative plural here, because it is the direct object of zostawiasz.

The singular is:

• klucz = key

The plural is:

• klucze = keys

For this noun, the nominative plural and accusative plural look the same:

• klucze = keys

So in this sentence:

• zostawiasz klucze = you leave the keys

Zostawiasz is the imperfective form, and it fits a general / repeated / habitual situation:

• kiedy zostawiasz jej klucze = when you leave her the keys

This sounds like a general question about what happens in such situations.

If you used the perfective zostawisz, it would sound more like a single future act:

• kiedy zostawisz jej klucze = when you leave her the keys (on one future occasion)

So the original sentence is asking about a general pattern, not one specific future moment.

Yes. Here kiedy means when and introduces a subordinate clause:

• kiedy zostawiasz jej klucze = when you leave her the keys

In this kind of sentence, it can also have a whenever feeling, depending on context.

A similar word is gdy, which also means when:

• Czy ufasz swojej współlokatorce, gdy zostawiasz jej klucze?

That version is also correct, though kiedy is very common and natural.

Because in Polish, a subordinate clause introduced by words like kiedy is normally separated by a comma.

So:

• Czy ufasz swojej współlokatorce, kiedy zostawiasz jej klucze?

This is standard Polish punctuation.

English sometimes uses fewer commas in similar sentences, so this is something learners often have to get used to.

No. Polish word order is fairly flexible, because endings carry much of the grammatical information.

The given order is natural and neutral:

• Czy ufasz swojej współlokatorce, kiedy zostawiasz jej klucze?

But other orders are possible, with different emphasis, for example:

• Czy swojej współlokatorce ufasz, kiedy zostawiasz jej klucze?
• Czy ufasz swojej współlokatorce, kiedy jej zostawiasz klucze?

These alternatives are possible, but the original version is the most straightforward for a learner.

Yes. That is a very natural English way to express the same idea.

Literally, the Polish is closer to:

• Do you trust your roommate when you leave her the keys?

But in natural English, you might also say:

• Do you trust your roommate when you leave the keys with her?

Both capture the same meaning well.

You would change the feminine forms to masculine ones:

• Czy ufasz swojemu współlokatorowi, kiedy zostawiasz mu klucze?

Changes:

• swojej → swojemu
• współlokatorce → współlokatorowi
• jej → mu

So the grammar stays the same, but the forms change to match a masculine noun and pronoun.