Learn Swedish: Är boken dyr eller billig? - Is the book expensive or cheap?

eller means 'or'. It is a coordinating conjunction, which means it links two parts of a sentence that have the same role. Here, it connects the two adjective choices dyr (expensive) and billig (cheap).

Why does the sentence start with the verb Är?

In Swedish, you form a question by moving the verb to the very beginning of the sentence. A normal statement would be Boken är dyr (The book is expensive), so swapping the first two words creates the question format Är boken...

Why do we use dyr and billig instead of dyrt and billigt?

Adjectives in Swedish must match the noun they describe. Because en bok is an en-word, the adjectives use their basic form. If we were talking about an ett-word like ett hus (a house), we would need to add a -t to the adjectives: dyrt and billigt.

Why is the word for book written as boken?

In Swedish, the word for 'the' attaches to the end of the noun as a suffix. The base word is bok (book). Since it is an en-word, we add the suffix -en to get boken (the book).