Questions & Answers about Skríða þeir hratt undir girðinguna?
Why is girðinguna in the accusative case here instead of the dative case?
The preposition undir (under) takes the accusative case when it shows movement to a new destination. Because they are crawling to get under the fence, it is accusative. If they were already under the fence and just crawling around in that spot, it would take the dative case.
How is the word girðinguna formed?
It is made of the feminine noun girðing (fence) plus the attached definite article -una (the). The ending is -una instead of the dictionary form -in because the word must be in the accusative case after this preposition.
Why do we use hratt here instead of the base adjective hraður?
Hratt is acting as an adverb here, meaning fast or quickly, because it describes how they crawl. In Icelandic, you usually create an adverb by taking the neuter singular form of an adjective.
Why does the sentence start with the verb Skríða?
Icelandic does not use helping verbs like do or does to ask questions. Instead, you simply swap the subject and the verb. Þeir skríða means they crawl, and swapping them to Skríða þeir turns it into the question Do they crawl?.