If you want an adverb to describe the way someone sings, how about 'tunefully', 'melodiously', 'loudly', or 'badly', for example?
If you want an adverb that is derived from the verb 'to sing', I offer 'singingly'.
loudly
to yourself.
To Yourself
No, it is the present participle of "to sing" and may be a verb, noun (gerund), or adjective (e.g. singing carolers).
tunefully is the adverb, most tunefully the superlative. She sang most tunefully
Melodiously.
loudly
Sung is not an adverb because and adverb describes how,when,where, and what. Sung is the past participle of the verb "to sing."
adverb
It's a question where you use how and adverb to find out how the action is done, i.e.; how fast can she run? how beautifully does the bird sing?
to yourself.
to yourself for A+
to yourself for A+
to yourself for A+
to yourself for A+
to yourself for A+
horribly beautifully raucously moodily