Adverbs are normally used with a verb to express an action is done (how, when, where, with how much intensity, to what extent). Respectively there are adverbs of manner, time, place, intensity, quantity.
Adverbs of manner are usually formed by adding -ment to the adjective(same as ly in english)
If the adjetive ends in a consonant ment is added to its feminine form
Adjective(masc, fem)
Adverb
doux, douce(soft)
doucement(softly)
franc, franche(frank)
franchement(frankly)
final, finale(final)
finalement(finally)
If the adjetive ends in a vowel ment is added to its masculine form
Adjective(masc, fem)
Adverb
absolu(absolute)
adsolument(adsolutely)
désespéré(desperate)
désespérément(desperaltely)
vrai(true)
vraiment(truly)
simple(simple)
simplement(simply)
But:
Adjective(masc, fem)
Adverb
gai(cheerful)
gaiement/ gaîment(cheerfully)
nouveau(new)
nouvellement(newly)
vrai(true)
vraiment(truly)
fou(mad)
follement(madly)
e of feminine form is changed to é before adding
Adjective(masc, fem)
Adverb
commun(common)
communément(commonly)
précis(precise)
précisément(newly)
profond(deep)
profondément(deeply)
énorme(enormous)
énormément(enormously)
aveugle(blind)
aveuglément(blindly)
Adjective which are ending in ent and ant change to emment and amment
Adjective(masc, fem)
Adverb
prudent(careful)
prudemment(carefully)
évident(obvious)
évidemment(obviously)
brillant(brilliant)
brillamment(deeply)
But:
Adjective(masc, fem)
Adverb
lent(slow)
lentemment(slowly)
irregular adverbs
Adjective(masc, fem)
Adverb
bon(good)
bien(well)
bref(brief)
brièvement(briefly)
gentil(kind)
gentiment(kindly)
mauvais(bad)
mal(badly)
meilleur(better)
mieux(better)
Some adjectives are directly used as adverbs in certain expressions
-parler bas/ haut or fort(to speak softly/ loudly)
-coûter/payer cher(to cost/pay a lot)
-s'arrêter court(to stop short)
-couper court(to cut short)
-voir clair(to see clearly)
-marcher droit(to walk straight)
-travailler dur(to work hard)
-chanter faux/juste(to sing off key/in tune)
-sentir mauvais/bon(to smell bad/good)
-refuser net(to refuse point blank)
In French after the verbs of saying and looking + adjective, the phrase is often translated to an adverb
-"tu m'écriras ?" dir-il d'une « voix triste » (will you wrte to me ? he said « sadly »)
-elle nous a regardés d'un air « dédaigneux » (she looked at us disdainfully)
Preposition followed by noun can be expressed as adverbs
sans soin (carelessly)
avec fierté (proudly)
avec amour (lovingly)