Learn Hardcore Ukrainian: Я ношу книгу в рюкзаку.

Ношу comes from the infinitive носити, which is an imperfective, multidirectional verb meaning “to carry” (habitually or generally). Its perfective counterpart is понести, and there’s also a unidirectional imperfective нести used for a single‐way action right now.

What case is книгу, and why does it end in -у instead of -а?

Книгу is in the accusative singular. In Ukrainian, most feminine nouns ending in -а replace that ending with -у in the accusative (direct‐object) form.

Why is the preposition в used with рюкзаку, and what case is рюкзаку?

Here в means “in” and expresses location, so it governs the locative case (also called the prepositional). The locative singular of рюкзак is рюкзаку, hence в рюкзаку = “in the backpack.”

Why is it в рюкзаку instead of у рюкзаку?

Ukrainian alternates в and у for “in.” You use в before words starting with a single consonant (в рюкзаку, в місті) and у before words starting with two or more consonants (у школі, у спортзалі) or a vowel cluster that’s hard to attach to в.

Can the subject pronoun я be omitted in Я ношу книгу в рюкзаку?

Yes. Because Ukrainian verb endings mark person and number, you can say Ношу книгу в рюкзаку and it’s clear you mean “I carry…” Including я adds emphasis (e.g. “I do carry…”).

How flexible is the word order in this sentence?

Thanks to case endings, word order is fairly free. The neutral order is Subject–Verb–Object–Circumstance: Я ношу книгу в рюкзаку. You can shift elements for focus, e.g.:

У рюкзаку я ношу книгу (emphasizing the backpack)
Я в рюкзаку ношу книгу (emphasizing location)
Я ношу в рюкзаку книгу (mild emphasis on the object).

Why use the imperfective ношу here instead of a perfective form?

Imperfective ношу describes an ongoing or habitual action: “I carry/habitually keep the book in my backpack.” A perfective verb would imply one completed trip or action.

How would you express “I will carry the book in my backpack” as a one‐time action?

Use the perfective infinitive понести in the future:
Я понесу книгу в рюкзаку.
That means “I will carry the book [once] in my backpack.”

What’s the difference between носити and нести?

Both mean “to carry,” but нести is unidirectional imperfective (one‐way, right now), e.g. Я несу сумку додому (“I’m carrying the bag home [this one trip]”). Носити is multidirectional or habitual (repeatedly, over time), e.g. Я ношу книгу в рюкзаку (“I carry/habitually have the book in my backpack”).

Can носити also mean “to wear” like clothes?

Yes. Носити covers “to wear” garments or accessories. For example, Я ношу шапку means “I wear a hat.”