Biblioteka jest cicha, dlatego uczę się tam szczególnie wieczorem.

to be

Breakdown of Biblioteka jest cicha, dlatego uczę się tam szczególnie wieczorem.

• wieczorem: in the evening
• tam: there
• dlatego: therefore

Questions & Answers about Biblioteka jest cicha, dlatego uczę się tam szczególnie wieczorem.

Why is cicha used instead of cicho?

In Polish, adjectives agree with the noun they describe in gender, number, and case. Biblioteka is a feminine noun in the nominative singular, so you need the feminine adjective form cicha (“quiet”). Cicho is an adverb (“quietly”), which would describe a verb, not the library.

What exactly is dlatego and how does it function in the sentence?

Dlatego is a conjunctive adverb meaning “therefore” or “that’s why.” It links the first clause (“The library is quiet”) to the second (“I study there…”), showing cause and effect. It always needs a comma before it when it connects two independent clauses.

Could we replace dlatego with więc or zatem, and are there any differences?

Yes. You can say więc (“so/then”) or zatem (“thus”) in place of dlatego with almost the same meaning.

• więc is more conversational:
  Biblioteka jest cicha, więc uczę się tam wieczorem.
• zatem is slightly more formal:
  Biblioteka jest cicha, zatem uczę się tam wieczorem.
  In each case, you still use a comma before the word.

Why does the verb uczę się immediately follow dlatego?