Yes, an adverb can modify another adverb. Example sentence: That was really truly the best movie ever.
"Considerably" is an adverb.
Yes it can
Yes. It can modify another adverb.Thanks for asking your question.Bye Bye now.
The very new video game has sold out. the verb is - has sold out (present perfect, main verb sold out) adverb #1 is - new modifying video adverb #2 is - very modifying new