Breakdown of Ona czytała, a w międzyczasie ja sprzątałem.
ona
she / it (f)
ja
I
czytać
to read
a
and / whereas (contrast)
Questions & Answers about Ona czytała, a w międzyczasie ja sprzątałem.
Why is the word a used here instead of i to mean "and"?
In Polish, a is a conjunction used to show a slight contrast or to compare two different subjects doing different things at the same time. Because we are contrasting what she was doing (Ona czytała) with what I was doing (ja sprzątałem), a is the natural choice. Using i would sound unnatural here because i is mostly used for adding similar things together without contrasting them.
Polish usually drops subject pronouns like ja (I). Why is it included here?
You are right that the verb ending in sprzątałem already tells us the subject is a masculine "I". However, Polish includes the pronoun when emphasizing a contrast. By explicitly saying Ona czytała, a w międzyczasie ja sprzątałem, the speaker is deliberately highlighting the difference between the two people and their simultaneous activities.
Both verbs here (czytała and sprzątałem) are imperfective. Is that required when using w międzyczasie?
Yes, generally. Because w międzyczasie means "in the meantime," it sets up a situation where actions are ongoing and overlapping. Imperfective verbs are used for continuous, unfinished actions in the past. If you used perfective verbs, it would mean the actions were fully completed one after another, which would clash with the meaning of "in the meantime."
How is the phrase w międzyczasie formed?