I learned this way:
He gave me this pen.
->I was given this pen by him.
->This pen was given to me by him.
***** NOT A TEACHER *****
Hello,
I believe that your teachers did a good job, and I should most respectfully suggest that you continue to use the "to" until you learn more English and then maybe you can start dropping the "to" in some cases.
As bhaisahab told you, native speakers sometimes drop the "to." This often happens in
passive sentences after
certain verbs.
(1) Here is an example from one expert's book:
A car was
given (to) me by my father.
(2) Here are three examples from another expert:
(a) The property was
left her by her husband.
(b) Justice shall be
done everybody.
(c) Had time been
permitted him, he would have ....
(3) My books listed some verbs that allow the "to" to be dropped in passive sentences. I have used these verbs in some sentences. Please remember: These are only my sentences. If they are wrong, I am to be blamed. They were
not in the books that I checked.
(a) Riches were
promised me if I bought a lottery ticket.
(b) A promotion at work was
refused me because I am old and ugly.
(c) Lies are often
told us by the government.
(d) $1,000 was
offered me if I should tell a lie. Of course, I refused. I should not tell a lie even if $10,000 were
offered me!
(e) $500 is
owed me by my so-called best friend, but I don't think that I will ever see the money again.
(f) The information was secret, but it was quietly
shown me by my manager's secretary.
(4) Well, I think that you get the idea. When you read English, don't be astonished (surprised) if a "to" is missing. Native
speakers often do this. If you are not sure about a particular sentence without "to," just post it here, and a native speaker will
comment on it. Unfortunately, grammar books do not seem to comment very much on this matter. I cannot find a complete explanation.
*****
Some of the experts were:
Michael Swan,
Practical English Usage.
L.G. Alexander,
Longman English Grammar.
Otto Jespersen,
Essentials of English Grammar.
HAVE A NICE DAY!