Breakdown of Le noyau est revêtu d'une substance inconnue.
être
to be
une
a / an (feminine)
de
of / from / any (in negative sentences) / about (concerning)
inconnu
unknown
Questions & Answers about Le noyau est revêtu d'une substance inconnue.
Why do we use d' (short for de) here instead of par for the passive agent?
In the French passive voice, the agent (the thing doing the action) is usually introduced by par. However, verbs expressing a state of being, an emotion, or a physical covering (like revêtir, couvrir, or entourer) use de. Because the substance is simply covering the nucleus as a state rather than actively performing a dynamic action, de is the correct choice.
Can I use avec instead of de, since the English translation is "coated with"?
No, avec would sound unnatural here. In French, when a material completely covers an object in a passive construction, the material is treated as the agent of the verb, which requires de. The word avec is mostly reserved for the tool or instrument used to perform a specific action (like painting with a brush), not the covering material itself.
What verb does revêtu come from, and how is it formed?
It is the past participle of revêtir, which means to coat, cover, or don (put on clothing). It is an irregular verb that follows the exact same conjugation pattern as vêtir (to dress).
If the subject was feminine instead of masculine, would revêtu change?