1) Personal Passive

When we put an object of an active sentence into passive, it becomes subject of the passive sentence.

Active voice:
The professor explained the students the exercise.
The professor explained the exercise to the students.

Passive voice:
The students were explained the exercise.
The exercise was explained to the students.

We sometimes use a pronoun for “the students” or “the exercise” in its subject form (here: they/it).

Passive voice:
They were explained the exercise.
It was explained to the students.

We very often leave out the by-agent in the passive sentence (here: by the professor).


2) Impersonal Passive – It is said …

The phrase It is said … is an impersonal passive construction. We often use it in news.

Passive sentence – version 1:
It is said that children are afraid of ghosts.

Passive sentence – version 2:
Children are said to be afraid of ghosts.

The correct active sentence would be:
Active sentence: People say that children are afraid of ghosts.