The document discusses how to change sentences from active to passive voice. It explains that the passive voice is used when the subject is unimportant or unknown. To form the passive, the verb "to be" is used along with the past participle of the main verb. The original subject becomes the object, preceded by the preposition "by". Tenses like simple present, past, perfect, and future are transformed by changing the verb to the appropriate passive form. Pronouns in the original subject become the subject in the passive.

2.  To indicate that what is important is the
action and the subject is unimportant or
unknown.
 To prevent an active sentence whose subject
would they, somebody, someone, etc.

3.  It is formed with the verb to be more the past
participle of the main verb.
 Passing to a sentence to passive gets to be at
the same time I had the verb in the active
voice.
 The subject is placed at the end of the
preposition preceded by.

4.  Present Simple:
 He opens the door / The door is opened by
him
 Past Simple:
 He opened the door/ The door was opened
by him

5.  Present Perfect:
 He has opened the door / The door has been
opened by him
 Past Perfect Simple:
 He had opened the door / The door had been
opened by him

6.  Future Simple:
 He will open the door / The door will be
opened by him
 Be going to:
 He is going to open the door / The door is
going to be opened by him

7.  Modal verbs (must, can , should):
 He can open the door / The door can be
opened by him

8.  If the subject of the active sentence is a
personal pronoun, active is changed by its
object pronoun (me, you, him, her, it, us,
you, them)
 If there is a direct and indirect complement
the active sentence, the two can be the
subject of the passive sentence.

9.  If the indirect object is a pronoun, in the
passive form must be used subject.
 If the sentence active there is a modal verb or
be going to, put in passive verb that follows.

10.  They buy newspapers / Newspapers are
bought by them
 I saw the film / The film was seen by me
 We have cooked a chicken / A chicken has
been cooked by us
 Tourism had increased benefits / Benefits had
been increased by tourism
 She will sing a song / A song will be sung by
her