Questions & Answers about Þú varst að keyra án bílbeltis.
Why does the sentence use bílbeltis instead of the base word bílbelti?
The preposition án (without) is one of the specific prepositions that forces the noun following it into the genitive case. Since the base word is bílbelti, it takes the -s ending to become the genitive bílbeltis.
How does varst að keyra translate to 'were driving'?
Icelandic shows ongoing actions using the verb vera (to be) followed by að and the infinitive of the action verb. This is just like the English '-ing' ending. Þú varst means 'you were', so varst að keyra means 'were driving'.
Is bílbelti a compound word? How does that affect its case endings?
Yes, it is made of bíll (car) and belti (belt). When compound words change case, only the very last word in the chain changes. That is why belti turns into beltis after the preposition án, while the bíl- part stays exactly the same.
What gender is bílbelti, and how does its genitive ending help show that?
It is a neuter noun. A great tip to remember is that most nouns ending in -i that just add an -s in the genitive case (turning belti into beltis) are neuter.