Learn Hardcore Russian: Я читаю книгу без перерыва.

Без перерыва translates to "without a break". It functions as an adverbial modifier that explains how the action of reading is performed—that is, continuously without stopping. Also, note that the preposition без requires the noun that follows to be in the genitive case, which is why we have перерыва.

Why is книгу in the accusative case, and what does that indicate about its role in the sentence?

The noun книгу is in the accusative singular because it is the direct object of the verb читать. In Russian, the direct object (the entity being acted upon) takes the accusative case, signaling that it is the book being read.

Why doesn't this sentence include an article (like "a" or "the") before книгу, as one would in English?

Russian does not have articles. Definiteness or indefiniteness is conveyed through context, word order, or additional descriptive words rather than by using words like a or the. Thus, книгу stands alone without any article.

How is the verb читаю conjugated here, and why is the present tense used even if the action is ongoing?

Читаю is the first-person singular form of the verb читать in the present tense. Russian does not have a distinct present continuous tense like English does; the simple present can describe both habitual actions and actions happening right now. So, Я читаю книгу appropriately conveys that the speaker is currently reading a book or reads it regularly.

Is it necessary to include the subject pronoun Я in the sentence, or can it be omitted?

In Russian, subject pronouns (like Я) are often omitted because the verb form usually makes the subject clear. However, including Я can add emphasis or clarity, which is why it's present here. In informal contexts, you might hear just читаю книгу without the subject.