коли (сполучник часу)

In Ukrainian, коли is a temporal conjunction used to build complex sentences. Here are the key rules to become proficient in its use:

• The Question Word: Beyond joining sentences, коли is the primary word used to ask 'When?' in direct questions.
• Relative Adverb: Коли can also act as a relative word to describe a noun related to time (e.g., день, коли ми зустрілися - the day when we met).
• The Comma Rule: You generally place a comma before коли if it introduces a subordinate clause in the middle of a sentence. If the коли-clause starts the sentence, the comma goes after the entire clause. However, exceptions exist: no comma is used if the clause consists of just the word коли (e.g., Він пішов, але не сказав коли), if it is preceded by не (e.g., не коли це сталося, а чому), or in certain set phrases.
• Habitual or General Actions: To describe routines or general truths in the present, use the present tense in both clauses (e.g., Коли йде дощ, я залишаюся вдома - When it rains, I stay home).
• Future Tense Agreement: In English, we say 'When I arrive (present), I will call.' In Ukrainian, if the event is in the future, the коли-clause must be in the future tense: Коли я прийду (future), я подзвоню. This applies even if the main clause uses an imperative command (e.g., Коли я прийду, подзвони мені!).
• Aspect in Future Clauses: When using the future tense with коли, choose the perfective aspect for completed actions (e.g., Коли я прочитаю книгу, я її віддам - When I finish reading the book, I will return it) and the imperfective aspect for ongoing or repeated actions (e.g., Коли я читатиму, я питиму чай - When I am reading, I will drink tea).
• Interrupted Actions in the Past: A common pattern is using коли to introduce a sudden, completed action (perfective aspect) that interrupts an ongoing background action (imperfective aspect). For example: Я готував вечерю, коли задзвонив телефон (I was cooking dinner when the phone rang).
• Simultaneous or Repeated Past Actions: To describe actions happening at the same time or repeatedly in the past, use the imperfective aspect in both clauses (e.g., Коли ми жили в Києві, ми часто ходили в театр - When we lived in Kyiv, we often went to the theater).
• Time vs. Condition: While якщо is strictly used for conditions ('if'), коли is more flexible. It primarily indicates time ('when'), but can also express simple conditions (e.g., Коли хочеш, я прийду - If you want, I will come). A common way to form hypothetical conditions is by combining it with the particle б/би to form the conditional mood (e.g., Коли б я знав, я б допоміг - If I had known, I would have helped), which is known as умова з коли б.
• The Synonym 'як': In spoken and literary Ukrainian, як is frequently used as a direct synonym for коли in time clauses (e.g., Як прийду, подзвоню - When I arrive, I will call).
• Correlative Pairs: For emphasis or clarity, the main clause often begins with то or тоді (e.g., Коли закінчиш, то подзвони - When you finish, then call). То is particularly common in spoken Ukrainian.