Form

The passive of an active tense is formed by putting the verb to be into the same tense as the active verb and adding the past participle of the active verb. Only transitive verbs can have a passive form. The subject of the active verb becomes the ‘agent’ of the passive verb. The agent is very often not mentioned. When it is mentioned it is preceded by by and placed at the end of the clause.
However,when with is used and not by, it means that we are dealing with the material, tool or instrument used, not with the agent. In this case the two sentences have different meaning:

hirdetés

He was killed by a (falling) brick. = A (falling) brick killed him. (it was an accident)
He was killed with a brick. = The man who killed him used a brick. (it was no accident)

Active Tenses And Their Passive Equivalents

Tense/Verb form

Active tense

Passive voice

Simple present

keeps

is kept

Present continuous

is keeping

is being kept

Simple past

kept

was kept

Past continuous

was keeping

was being kept

Present perfect

has kept

has been kept

Past perfect

hadkept

had been kept

Future

will keep

will be kept

Conditional

would keep

would be kept

Perfect conditional

would have kept

would have been kept

Present infinitive

to keep

to be kept

Perfect infinitive

to have kept

to have been kept

Present participle/gerund

keeping

being kept

Perfect participle

having kept

having been kept

Other continuous tenses are exceedingly rarely used in passive.

Uses Of Passive

The passive is used:
1. When it is not necessary to mention the doer of the action as it is obvious who he is/was/will be.

hirdetés

2. When we do not know, or do not know exactly, or have forgotten who did the action.

3. When the subject of the active verb would be ‘people’.

4. When the subject of the active sentence would be the indefinite pronoun one.

5. When we are more interested in the action than the person who does it.

6. The passive may be used to avoid an awkward or ungrammatical sentence. This is usually done by avoiding a change of subject.

7. The passive is sometimes preferred for psychological reasons. A speaker may use it to disclaim responsibility for disagreeable announcements.

Examples

Simple present
“I find that, howsoever men speak against adversity, yet some sweet uses are to be extracted from it; like the jewel, precious for medicine, which is taken from the head of the venomous and despised toad.”

“Én úgy látom, bárhogyan is beszélnek az emberek a balsors ellen, de valami előnyt mégis lehet nyerni belőle, akárcsak a mérges, utálatos varangyos béka fejéből a gyógyereje miatt értékes gyöngyöt.” (Lamb,p86)

Simple past
“From this loving conference she was called away by her nurse, who slept with her, and thought it is time for her to be in bed, for it was near to day-break; ”
“E szerelmes beszélgetésből Júliát elszólította dajkája, aki az ő szobájában szokott aludni, és úgy gondolta, ideje már, hogy Júlia lefeküdjék, hiszen nemsokára hajnalodik.” (Lamb,p6)

Present perfect
“Helena, as has been before related, endeavoured to keep pace with Demetrius when he ran away so rudely from her;but she could not continue this unequal race long…”
“Helena, mint ahogy elbeszéltük, igyekezett lépést tartani Demetriusszal, aki olyan durván elrohant tőle, de nem bírta sokáig ezt az egyenlőtlen versenyfutást…” (Lamb,p66)

Past perfect
“They found that it was likely to prove a very tragical sight; for a large and powerful man, who had long been practised in the art of wrestling…”
“Úgy látták, hogy valószínű tragikus látványban lesz részük, mert egy izmos, hatalmas férfi, aki régóta űzte a birkózás művészetét…” (Lamb, p196)

Future
“See! The vessel will be dashed to pieces.”
“Nézd csak! A vitorlás rögtön darabokra törik.” (Lamb, p198)

Conditional

“…was just going to wrestle with a very young man, who, from his extreme youth and inexperience in the art, the beholders all thought would certainly be killed.”
“…éppen egy nagyon fiatal emberrel készül megmérkőzni, akiről valamennyi néző azt gondolta, hogy megölik, olyan fiatal volt, és olyan tapasztalatlan a birkózásban.” (Lamb, p88)

Present infinitive
“…but for poor Lysander to be forced by a fairy love-charm to forget his own true Hermia, and to run after another lady…”
“De így szegény Lysandernek igazán szomorú véletlen volt, hogy e tündéries szerelmi varázs arra kényszerítette, hogy elfeledje hű Hermináját, és egy másik hölgy után szaladjon…” (Lamb, p66)

Present participle/gerund

“The dance being done, Romeo watched the place where the lady stood;”
“Amikor a tánc véget ért, Rómeó megfigyelte, hol áll meg a hölgy” (Lamb, p10)

Perfect participle
“…and having been for some time displeased with her niece, because the people praised her for her virtues, and pitied her for her good father’s sake…”
“Már egy idő óta sehogy sem volt ínyére az unokahúga sem, mert a nép dícsérte erényeit, és sajnálta jó apja miatt.” (Lamb, p92)

Auxiliary + infinitive combinations are made passive by using a passive infinitive(tempest)

“You must be brought, I find, for the lady Mirinda to have a sight of your pretty person.”
“El kell, hogy vigyelek az úrnőm, Mirinda elé, azt hiszem, azért, hogy meglássa csinos személyedet.” (Lamb, p206)


Examples from Newsweek:


Simple present:

“…our new Ultimo seats from Italy are electrically controlled…” (p1)
“A mi új, olasz Ultimo nevű üléseink elektromosan vezéreltek.”

Simple past:

“Last weekend Betancourt was housed in a U. S. diplomatic residence in Santo Domingo…” (p5)
“Múlt hétvégén Betancourtot egy amerikai diplomáciai rezidencián szállásolták el Santo Domingoban.”

“Glass everywhere was shattered, and cafeteria tables were upturned and littered with food.”
(p78)
“Az üveg mindenütt össze volt törve, és az étterem asztalai fel voltak fordítva és tele voltak szórva étellel.”

Present perfect:

“While in the rest of Europe many people have been freed from domination and have achieved democratic rights, the Serbs in Yugoslavia still believe they can dominate the Albanian Kosovars by force.” (p12)
“Míg Európa nagy részén sok ember szabadult fel az uralom alól és nyerte el a demokratikus jogokat, addig a szerbek Jugoszláviában még mindig azt hiszik, hogy erőszakkal uralkodhatnak az koszovói albánok felett.”
“Throughout its 100-year history of making cars, Opel has been known as a vital ingredient of progress.” (p19)
“Az autogyártás 100 éves története során az Opelt úgy ismerik, mint a fejlődés egyik alapvető tartozéka.”

Past perfect:
“Lisa Kreutz, 18, had been shot at least six times.” (p79)
“A 18 éves Lisa Kreutzot legalább hatszor meglőtték.”

Conditional:

“If Russia supported Belgrade, great powers would be aligned on competing sides of a Balkan conflict.” (p21)
“Ha Oroszország támogatná Belgrádot, hatalmas erőket sorakoztatnának fel egy balkáni ellentét versengő oldalain.”

Present infinitive:
“..they are likely to be joined by U. N. Secretary-General Kofi Annan.” (p22)
“Valószínű, hogy az ENSZ főtitkár Kofi Annan csatlakoztatni fogja őket.”

“We’re certainly not going to be stopped by forces like Slobodan Milosevic’s.” (p24)
“Biztosan nem fognak minket olyan erők megállítani, mint Slobodan Milosevicé.”

Auxiliary+infinitive:

“The war in Kosovo should be viewed no differently.” (p16)
“A koszovói háborút is pontosan így kellene szemlélni.”


Infinitive Constructions After Passive Verbs

A .Expressions of the type they/people+say/believe, etc., Are frequently used in the passive in formal speaking and writing. Other verbs which are used in this pattern are: assume, feel, find, presume, repute, understand, claim, report, think, know, etc. Sentences of this type have two possible passive forms: It is known that he is…/He is known to be…

B. After suppose

1. In the passive can be followed by the present infinitive of any verb but this construction usually conveys an idea of duty and is not therefore the normal equivalent of suppose in the active:
You are supposed to know how to do it = { It is your duty to know how to do it.
You should know how to do it.

2. Suppose in the passive can similarly be followed by the perfect infinitive of any verb.

C. The continuous infinitive can be used after the passive of believe, know, report, say,
suppose, think, understand:
People think that he is living abroad. = He is thought to be living abroad.

Sources:
Thomson, A.J.& Martinet, A.V. – A Practical English Grammar, Oxford University Press Lamb, Mary & Charles – Tales from Shakespeare – Shakespeare-mesék, Noran könyvkiadó
Allsop, Jake – Cassell’s Students’ English Grammar, Cassell Publishers Limited
Newsweek (May 3,1999.)