Hello, hoangkha.:-D
Well, of course, there are exceptions. They make language interesting in my opinion.
Let me share with you some information on this topic, which is from a grammar book written by a world-renowned author:
4 much or very with past participles
When a past participle is part of a passive verb, we can put much or very much before it, but not very.
He's (very) much admired by his students. (NOT ... [STRIKE]very admired [/STRIKE]...)
Britain's trade position has been (very) much weakened by inflation. (NOT ... [STRIKE]very weakened [/STRIKE]...)
When a past participle is used as an adjective, we usually prefer very. This is common with words referring to mental states, feelings and reactions.
a very frightened animal (NOT [STRIKE]a much frightened animal[/STRIKE])
a very shocked expression
The children were very bored.
She looked very surprised.
Common exceptions:
That's Alice, unless I'm (very) much mistaken. (NOT ... [STRIKE]unless I'm very mistaken.[/STRIKE])
He's well known in the art world. (NOT ... [STRIKE]very known [/STRIKE]...)
(Michael Swan Practical English Usage Third Edition page 381)