Breakdown of Kiedy się przyznał, zrozumiałem to, co ukrywał.
to
this
co
what
kiedy
when
zrozumieć
to understand (perfective)
Questions & Answers about Kiedy się przyznał, zrozumiałem to, co ukrywał.
Why does the sentence use to, co instead of just co for "what"?
In English, you can just say "I understood what he was hiding." In Polish, when "what" connects two parts of a sentence like a noun, it is typically split into two words: a pointer in the first half (to - "that" or "the thing") and a connector for the second half (co - "which"). Literally, you are saying "I understood that, which he was hiding."
Do I always need a comma between to and co?
Yes! Polish punctuation rules are strict about separating clauses. Because co starts a new subordinate clause (a sentence part containing its own verb, ukrywał), you must always place a comma right before it to separate it from the main clause.
Why are przyznał and zrozumiałem perfective, but ukrywał is imperfective?
This sentence perfectly shows how Polish uses aspect in storytelling. Przyznał się (he confessed) and zrozumiałem (I understood) are completed, one-time actions, so they use the perfective aspect. However, ukrywał (he was hiding) describes an ongoing background action that was happening leading up to the confession, which requires the imperfective aspect.
Why is się placed right after Kiedy instead of next to its verb (przyznał)?