Please don't assume that passives always need "by". I know your books might tell you this,but you should know that all verbs in the passive voice are not exclusively followed by "BY".
A few examples in which agents, in Passive Voice, are positioned after some other prepositions, like about, at,–‘to’, ‘with’, etc. instead of the preposition –‘by’.
e.g.:-
Active
Passive
(i)
I know him.
He is known to me.
(ii)
He annoyed me much.
I was much annoyed with him.
(iii)
My frequent Visit annoys him.
He is annoyed at my frequent visit.
(iv)
His carelessness annoys me much.
I am annoyed about his carelessness.
(v)
The precocity of the child astonished me.
I was astonished at/by the precocity of the child.
(vi)
A large number of trees surround the village.
The village is surrounded with/by a large number of trees.
A few examples in which agents, in Passive Voice, are positioned after some other prepositions, like about, at,–‘to’, ‘with’, etc. instead of the preposition –‘by’.
e.g.:-
Active
Passive
(i)
I know him.
He is known to me.
(ii)
He annoyed me much.
I was much annoyed with him.
(iii)
My frequent Visit annoys him.
He is annoyed at my frequent visit.
(iv)
His carelessness annoys me much.
I am annoyed about his carelessness.
(v)
The precocity of the child astonished me.
I was astonished at/by the precocity of the child.
(vi)
A large number of trees surround the village.
The village is surrounded with/by a large number of trees.
The verb 'know' in its passive voice is always followed by the preposition TO instead of BY without changing its meaning.
In passive sentences other prepositions[ of,from,at,with etc] can also be used.
EXAMPLES:
shoes are made of leather.
Bread is made from flour.
He is surprised at me
He was born in Kuwait.
The room was filled with smoke
In passive sentences other prepositions[ of,from,at,with etc] can also be used.
EXAMPLES:
shoes are made of leather.
Bread is made from flour.
He is surprised at me
He was born in Kuwait.
The room was filled with smoke