Including the agent

 Including the agent when:

A. It is surprising or unexpected

B. It is used to provide additional or new information

C. It is used to complete the meaning of the sentence or to add important information.

http://www.usingenglish.com/articles/use-by-agent-in-passive-voice.html

Verbs with no passive form

 A. Intransitive Verbs. They cannot be followed by objects. They have no passive forms

B. http://www.englishexercises.org/makeagame/viewgame.asp?id=8868. They can be followed by objects. Most transitive verbs have passive form, but some do not.

C. Verbs that are Intransitive or Transitive. Some verbs can be transitive or intransitive.

Reason for Using the Passive:

A. Focus on results or processes

B. Omitting the Agent (agentless passives). They are used when the agent is:

            Unimportant person

            Unknown Agent

            Obvious Agent

Used to avoid very general subjects such as people, someone, we, as and impersonal you and they.

Used to avoid taking responsibility for an action or to avoid blaming another person.

http://www.grammaring.com/verbs-which-cannot-be-used-in-the-passive-voice

http://www.grammar-quizzes.com/passive1d.html

Yes / No and Wh questions with passive voice:

Some examples:

Yes/No Questions

Simple Present Passive: Is the computer repaired? Yes, It’s / No, it isn’t.

Simple Past Passive: Was the computer repaired? Yes, It was / No, it wasn’t.

Present continuous passive: Is the computer being repaired? Yes, it’s / No, it isn’t.

Past continuous passive: was the computer being repaired? Yes, it was / No, it wasn’t.

Future passive with WILL: Will the computer be repaired? Yes, it will / No, it won’t.

Future passive with  BE GOING TO: Is the computer going to be repaired? Yes, it is / No, it isn’t.

Present perfect passive: Has the computer been repaired? Yes, it has / No, it has't.
Modal Passive: Could the computer be repaired? Yes, it could be / No, it couldn't be.
Phrasal modal passive: Does the computer have to be repaired?

Wh Questions

Simple Present Passive: When is the computer repaired?

Simple Past Passive: Where was the computer repaired?

Present continuous passive: How is the computer being repaired?

Past continuous passive: Why was the computer being repaired?

Future passive with WILL: Why will the computer be repaired?

Future passive with  BE GOING TO: Why is the computer going to be repaired?

Present perfect passive: Why has the computer been repaired?

Modal Passive: Why should the computer be repaired?

Phrasal modal passive: Why does the computer have to be repaired?

http://www.englisch-hilfen.de/en/grammar/questions_passive.htm

http://www.englishexercises.org/makeagame/viewgame.asp?id=8868

The Modal Passive

 Structure: MODAL + BE + PAST PARTICIPLE (+BY+NOUM)

Ex. The computer should be repaired.

https://www.youtube.com/watch?v=0COmUBQmzeg

http://www.learnamericanenglishonline.com/Green%20Level/G8%20Modal%20Passive.html

http://www.studyandexam.com/passive-voice-for-modal.html

The Present Perfect Passive

 Structure: HAS/HAVE + BEEN + PAST PARTICIPLE (+BY+NOUM)

Ex. The computer has been repaired.

http://www.ego4u.com/en/cram-up/grammar/passive/exercises?present-perfect

The Future Passive

Future passive with WILL

Structure: WILL/BE + PAST PARTICIPLE (+BY+NOUM)

Ex. The computer will be repaired.

http://www.ego4u.com/en/cram-up/grammar/passive/exercises?future-1

Future passive with BE GOING TO

Structure: BE GOING TO + BE + PAST PARTICIPLE (+BY+NOUM)

Ex. The computer is going to be repaired.

https://www.youtube.com/watch?v=tQ_s-OIfsf0

Present continuous passive and past continuous passive

 PRESENT CONTINOUS PASSIVE

Structure: AM/IS/ARE + BEING + PAST PARTICIPLE (+BY+NOUM)

Ex. The computer is being repaired.

http://www.ego4u.com/en/cram-up/grammar/passive/exercises?present-progressive

PAST CONTINOUS PASSIVE

Structure: WERE/WAS + BEING + PAST PARTICIPLE (+BY+NOUM)

Ex. The computer was being repaired.

http://www.ego4u.com/en/cram-up/grammar/passive/exercises?past-progressive

Simple present passive and Simple past passive

 SIMPLE PRESENT PASSIVE:

Structure: AM/IS/ARE + PAST PARTICIPLE (+BY+NOUM)

Ex. The computer is repaired.

SIMPLE PAST PASSIVE

Structure: WAS/WERE + PAST PARTICIPLE (+BY+NOUM)

Ex. The computer was repaired.

More information and some exercises:

http://www.ego4u.com/en/cram-up/grammar/passive/exercises

http://www.ego4u.com/en/cram-up/grammar/passive/exercises?02

 

https://elt.oup.com/student/solutions/preint/grammar/grammar_10_012e?cc=global&selLanguage=en

 

http://www.englishexercises.org/makeagame/viewgame.asp?id=1870

Active/Passive Overview

Active Sentences:


The professor                           teaches                     the students
Subject                                     Verb                        Object
(Doing actions)                                                        (Receiving actions)




Passive Sentences:
The students                            are taught                by  professor                  
Subject                                    Passive verb                  Object
(receiving actions)                                                       (doing actions)


Active/Passive overview: http://www.englishpage.com/verbpage/activepassive.html