Passive Voice - Two Objects

When there are two objects in an active sentence, there are two possible active sentences and two possible passive sentences.
possibility 1: The professor explained the students the exercise.
possibility 2: The professor explained the exercise to the students.
There are two objects in each of the following sentences:
object 1 = indirect object: the students
object 2 = direct object: the exercise
An indirect object is very often a person, a direct object a thing. When a direct object is followed by an indirect one, we put to in front of the indirect object.


active sentence - possibility 1
subject __________ verb ______ indirect object ______direct object
The professor ____ explained _____ the students ______ the exercise.


active sentence - possibility 2
subject __________verb________direct object_______indirect object
The professor ___ explained ______ the exercise ______ to the students.

Each of the objects (direct and indirect) can be the subject in the passive sentence.

passive sentence - possibility 1
subject _________ verb ________ object __________ (by-agent)
The students ____ were explained _ the exercise ______ (by the professor).

passive sentence - possibility 2

subject _________ verb ________ object __________ (by-agent)
The exercise ____ was explained __ to the students ____ (by the professor).