Breakdown of Lykillinn sem hún er að leita að er í bílnum.
vera
to be
bíllinn
the car
hún
she
í
in / into / to (before the hour, in telling time) / per (in frequency expressions)
Questions & Answers about Lykillinn sem hún er að leita að er í bílnum.
Why are there two aðs right next to each other in að leita að?
The first að is the infinitive marker used for the continuous tense er að leita (is searching). The second að is the preposition "for" from the phrase leita að (to search for). Because this is a relative clause with the word sem (that), the preposition gets stranded at the end of the clause, just like in the English translation: "searching for".
Since the phrase leita að requires its object to be in the dative case, why is lykillinn (the key) in the nominative case here?
In Icelandic relative clauses, the noun being described takes its case from its role in the main sentence, not from the relative clause. Here, the main sentence is Lykillinn er í bílnum (The key is in the car). Since the key is the subject of that main sentence, it must be in the nominative case.
Why does the word er appear twice in this sentence?
They act as verbs for two different parts of the sentence. The first er belongs to the relative clause hún er að leita að (she is searching for). The second er is the main verb of the entire sentence, connecting the subject to its location: Lykillinn ... er í bílnum (The key ... is in the car).
Why is bílnum in the dative case here?