Learn Hardcore Ukrainian: Нарешті вона натиснула кнопку і двері відкрилися. - Finally she pressed the button and the doors opened.

In Ukrainian, a comma is usually placed between two independent clauses joined by і/й: Нарешті вона натиснула кнопку, і двері відкрилися. However, the comma may be omitted when the clauses share a common element (here, the adverb Нарешті applies to the whole event) or when the actions are tightly linked in a cause‑and‑effect chain. The given version without the comma is acceptable. In formal writing, using the comma is the safer default.

Why does the verb end with -ла in натиснула?

Past-tense verbs in Ukrainian agree in gender and number:

він натиснув (masc.)
вона натиснула (fem.)
воно натиснуло (neut.)
вони натиснули (plural)

So with вона, the past form is натиснула.

Why is кнопка in the form кнопку?

Because it’s the direct object in the accusative case. Feminine nouns ending in -а take -у/-ю in the accusative singular: кнопка → кнопку. The verb натиснути “to press” takes a direct object: натиснути кнопку.

Can I say натиснула на кнопку instead of натиснула кнопку?

Yes. Both are common and correct:

натиснути кнопку (direct object)
натиснути на кнопку (with на + accusative) The version with на emphasizes the physical action a bit more, but in everyday speech they’re interchangeable.

Why is двері followed by a plural verb (відкрилися)?

Двері “door/doors” is plural-only in Ukrainian (pluralia tantum). Even when English would say “the door opened,” Ukrainian uses the plural and plural agreement: двері відкрилися, нові двері, важкі двері, etc.

What does the -ся in відкрилися mean?

The clitic -ся marks a reflexive/middle form. Here it makes the verb intransitive: “the doors opened (by themselves/as a result of something).” Compare:

Вона відкрила двері. “She opened the door(s).” (active, transitive)
Двері були відкриті. “The doors were open/opened.” (passive/result)
Двері відкрилися. “The doors opened.” (middle/reflexive, intransitive)

Is відчинилися better than відкрилися for doors?

Both are correct.

відчинити/відчиняти is the precise verb for opening doors/windows.
відкрити/відкривати is broader (“open a box/book/app,” and also doors in everyday usage). Many speakers say двері відкрилися; двері відчинилися is a bit more specific/stylistically neat.

Could I use й instead of і here? What about та or а?

і and й both mean “and.” Й is an euphonic variant often used after a vowel: …натиснула кнопку, й двері відкрилися. Both are fine here.
та also means “and” (stylistic alternative to і), especially to avoid repetition: …кнопку та двері.
а is contrastive (“and/but” in opposition). It wouldn’t fit here because there’s no contrast.

Why is Нарешті at the beginning? Could I move it?

Yes. Ukrainian word order is flexible. Placing Нарешті first sets the scene/emphasis on “finally” for the whole event:

Нарешті вона натиснула кнопку і двері відкрилися. (neutral, event-framing)
Вона нарешті натиснула кнопку… (slightly more focus on “she finally did it”) Avoid splitting it oddly (e.g., Вона натиснула нарешті кнопку is less natural).

Should there be a comma after Нарешті?

Usually no. Here Нарешті functions as an adverb meaning “finally,” not as a parenthetical. You’d add commas only if you use it as an actual parenthetical interjection (with a distinct pause), which changes the intonation: Нарешті, поїхали вже! In the given sentence, no comma is standard.

Why are both verbs perfective (натиснула, відкрилися)?

Perfective aspect presents single, completed actions and cause‑and‑effect sequence—exactly what’s happening: she pressed, the doors opened. Imperfective would change the meaning:

Вона натискала кнопку… “She was pressing/kept pressing…”
…двері відкривалися. “…the doors were opening (gradually/ongoing).”

Is відкрились (with -сь) okay instead of відкрилися?

Yes. The short clitic -сь is an accepted variant, especially after vowels and in more colloquial/poetic style: двері відкрились. The full -ся (відкрилися) is the neutral/standard form. Use one style consistently.

Can I drop the pronoun вона?

Grammatically, yes: Нарешті натиснула кнопку і двері відкрилися. However, in the past tense the verb shows gender/number but not person, so without вона the subject could be “she,” “I (female),” or “you (female)”—context must disambiguate. Keeping вона makes it explicitly “she.”

Could I use a dash to emphasize the quick result?

Yes. A dash highlights the immediate consequence:

Нарешті вона натиснула кнопку — і двері відкрилися. You may even omit і after the dash in a dramatic style: …натиснула кнопку — двері відкрилися.