Question 1

What tense/aspect is не смогу, and why is it used to mean “won’t be able”?

Accepted Answer

Смочь is the perfective counterpart of мочь (to be able). Perfective verbs in Russian do not have a present tense, so я смогу (“I will be able”) is a simple future form. Adding не gives не смогу = “I will not be able.”

Question 2

Why is прийти in the infinitive after смогу?

Accepted Answer

Modal verbs like мочь/смочь (can, be able) are followed by a second verb in the infinitive. Therefore смогу прийти literally means “I will be able to come.”

Question 3

Why is прийти perfective, and could I use the imperfective приходить here?

Accepted Answer

Прийти is the perfective form, indicating a single, completed action (arriving once). The imperfective приходить describes repeated or ongoing actions. Since you’re talking about one arrival tonight, you use прийти. Saying не смогу приходить would imply habitual or continuous coming, which doesn’t fit a one‑time event.

Question 4

What case is вечером, and how does сегодня вечером function in the sentence?

Accepted Answer

Вечером is the instrumental singular of вечер (evening), used adverbially to indicate time. Сегодня вечером = “this evening” is a time adverbial phrase telling us when the action happens. Russian word order is flexible, so you could also say Сегодня вечером я не смогу прийти without changing the basic meaning.

Question 5

Can I say Я не могу прийти сегодня вечером instead of не смогу? What’s the difference?

Accepted Answer

Yes. Я не могу прийти сегодня вечером uses present tense, imperfective не могу (I cannot), but it’s commonly used for future events with time markers. Subtle distinctions:
• не могу (present, imperfective) – more colloquial/familiar; can feel less formal.  
• не смогу (future, perfective) – more definite/formal; emphasizes a completed inability in the future.

Question 6

What’s the difference between прийти and приехать?

Accepted Answer

Both mean “to arrive/come,” but:  
• прийти (perfective of приходить) – “to come on foot.”  
• приехать (perfective of приезжать) – “to arrive by vehicle” (car, train, etc.).  
Use прийти if you arrive walking, приехать if by transport.

Question 7

Where does the stress fall in смогу and прийти?

Accepted Answer

• смогу – stress on the second syllable: смоГУ.  
• прийти – stress on the second syllable: приЙТИ.

Question 8

Does moving сегодня вечером to the front change the meaning? For example, Сегодня вечером я не смогу прийти.

Accepted Answer

You can freely move сегодня вечером to the front. Сегодня вечером я не смогу прийти places emphasis on when you can’t come but does not change the essential meaning.

Я не смогу прийти сегодня вечером.

Breakdown of Я не смогу прийти сегодня вечером.

Questions & Answers about Я не смогу прийти сегодня вечером.

More from this lesson

Master Russian — from Я не смогу прийти сегодня вечером to fluency