Learn Hardcore Russian: Я читаю книгу, потому что книга интересная. - I am reading a book because the book is interesting.

In Russian, it's quite common to repeat the noun for emphasis or clarity. In this sentence, книга appears first as the object of читаю ("I am reading the book") and then as the subject in the explanatory clause ("because the book is interesting"). Although in English you might replace the second mention with a pronoun, repeating the noun in Russian helps underline its significance in the context.

What tense is used in читаю, and what does it indicate about the action?

The verb читаю is in the present tense, which indicates that the action is currently happening or is a habitual action. This form tells us that the speaker is in the process of reading the book right now, and the interesting nature of the book is the reason behind that ongoing action.

Why does книга change to книгу in the sentence?

Книгу is the accusative form of книга. In Russian, the direct object of a verb takes the accusative case. Feminine nouns like книга typically change their ending (from -а in the nominative to -у or -ю in the accusative), which is why the sentence uses книгу after the verb читаю.

What is the function and meaning of потому что in this sentence?