Breakdown of Nous avons expliqué à l'assurance que nous avions rempli le constat.
nous
we / us (object pronoun)
avoir
to have
à
at / to / in (general locations) / about (what one thinks about / reacts to)
expliquer
to explain
Questions & Answers about Nous avons expliqué à l'assurance que nous avions rempli le constat.
Why do we use avions rempli (Plus-que-parfait) instead of avons rempli (Passé Composé) here?
This sentence is an example of reported speech in the past. Because the main verb (avons expliqué) is in a past tense, the reported action must shift one step further back in time. The original direct statement was 'Nous avons rempli le constat' (Passé Composé). When reported in the past, the Passé Composé backshifts to the Plus-que-parfait (avions rempli) to show that the filling out happened before the explaining.
Why is there an à in front of l'assurance?
In French, you explain something to someone. The verb structure is expliquer quelque chose à quelqu'un. Even though English speakers sometimes drop the preposition with similar reporting verbs (like 'we told the insurance company'), you must include the à in French to introduce who is receiving the information.
Is le constat a specific type of document?
Does l'assurance just mean the insurance policy, or the company itself?