Recently, I saw a definition describing "blind copy:"
A copy of a letter or the like, the original of which bears no evidence that the copy was sent to some other person.
In the expression above,is it correct to place a verb behind "Of which?"
I also saw a former example about "Of which" that writes like
The restaurant of which service satisfied me
At any rate,i just cannot get first definition sentence. I mean, why they use verb behind it rather than a noun. or the word behind the "of which" can be either a verb or a noun?