How do we know which form of adverb has to be used...the one ending in '...ment' or the regular form?
- Marie chante le plus fortement. V/S Marie chante le plus fort.
- Jeanne parle le plus doucement. VS Jeanne parle le plus doux.
- Il conduit le plus lentement. V/S Il conduit le plus lent.
How do we know which form of adverb to use in such situations?