The passsive mood

Yes, but in both passive cases you cannot use 'by him', because if you feel you must, then the sentence should not be cast in the passive voice.

Notice that MrM corrected the term "mood" to "voice" in his answer. The voices we have are the active and the passive. The moods that we have are the indicative, the subjunctive and the imperative.

Mr. Mikawber, thank you for answering my question.

But it is another point that i wan to know.

The girl was seen to enter the building.

This uses infinitive, because the original sentense uses bare infinitive.

"He saw the girl enter the building."

How about "He saw the girl entering the building."?

In this case, the sentense uses the pre

Please read my answer again, carefully. If you do, you will notice that it begins with the word 'Yes'.

Mr. Micawber, thank you very much.

I know the fact that I must not use the passive mood anytime; the active mood is natural and direct.

I really want to know only grammatically.

I have five reference books.

All say that "He saw a girl to enter the building."can be changed to "A girl was seen to enter the building."

But none says about"He saw a girl

The participle remains unchanged. It is not the main verb.

I saw her coming / She was seen coming
I asked her to come / She was asked to come
I am telling her to come / She is being told to come

Mr. Micawber, thank you very very much.

I have put your answer on my freference books.

I appreciate your kindn

The girl was seen to enter the building.

It's not wrong grammatically, but "entering" is what a native would say.

We can use participle in either active or passive context. Participle (clause) has no tense or voice restrications

This native would say 'entering' more often than he would say 'to enter'.