Breakdown of Båten hade sjunkit innan vi kunde sälja den.
vi
we
den
it (common)
ha
to have
kunna
to be able to, can
Questions & Answers about Båten hade sjunkit innan vi kunde sälja den.
Why is it sjunkit here instead of sänkt?
This highlights the difference between an intransitive verb (happening on its own) and a transitive verb (doing an action to something else). Sjunka (supine: sjunkit) means to sink by itself, which is what happened to the boat. Sänka (supine: sänkt) means to deliberately sink something else. If we had sunk the boat, it would be "vi hade sänkt båten".
Why do we use the form sjunkit rather than the past tense sjönk?
Because of the helper verb hade (had). In Swedish, any form of the verb ha (to have) must be followed by the supine form of the main verb. Sjönk is the simple past tense ("sank"), while hade sjunkit forms the past perfect ("had sunk").
The sentence ends with den for "it". Could we use det instead?
No, because "it" refers back to båten (the boat). Since en båt is an en-word, the pronoun for "it" must be den. If the sentence had used an ett-word for a vessel, such as ett skepp (a ship), the sentence would have ended with det.
Why is the verb sälja (sell) in its infinitive form here?