Sometimes an Intransitive Verb takes a Noun of kindred meaning for its object and this object is called Cognate object.
Intransitive Verb has object so voice change is not done. But if there is Cognate Object of Intransitive Verb it can be changed into Passive Voice.
Active Voice: I ran a race.
Passive Voice: A race was run by me.
Active Voice: He fought a good fight.
Passive Voice: A good fight was fought by him.
If it seems request, order, or warning in the Imperative Mood of Transitive Verb Let will be used at the beginning of the Passive Voice.
Structure- Let +sub+be+vpp+pre+ob+extension.
Active Voice: Do it.
Passive Voice: Let it be done.
Active Voice: Post the letter.
Passive Voice: Let the letter be posted.
Active Voice: Send for the man.
Passive Voice: Let the man be sent for.
Active Voice: Let him do the sum.
Passive Voice: Let the sum be done.
Active Voice: Tell us a story.
Passive Voice: Let a story be told.
Active Voice: Take care of your health.
Passive Voice: Let your health be taken care.
Structure- Let not +sub+be+vpp+pre+ob+extension.
Active Voice: Do not shut the door.
Passive Voice: Let not the door be shut.
***If it is Complex Sentence both Principal and Subordinate clause to be turned into Passive Voice.
***In this case ‘It’ is used at the beginning of the sentence.
Active Voice: I know that the boy said this.
Passive Voice: It is known to me that this was said by the boy.
Active Voice: Everybody says that they know it.
Passive Voice: It is said that it known to them.
*** In many cases there is no doer or agent in Passive Voice so on the basis of the meaning Subject is taken and changed into Passive Voice.
Active Voice: People did not build Rome in a day.
Passive Voice: Rome was not built in a day.
Active Voice: People call him a fool.
Passive Voice: He is called a fool.
*** If there is can/could/may/might/should/would in any sentence then be will be added with these words while changing from Active to Passive Voice.
Active Voice: I can do it.
Passive Voice: It can be done by me.
Active Voice: You could help me.
Passive Voice: I could be helped by you.
Active Voice: We should respect our parents.
Passive Voice: Our parents should be respected by us.
Some Transitive Verbs remain in Active form but these are used in Passive so these are called Quasi-Passive Verb.
Active Voice: Honey tastes sweet.
Passive Voice: Honey is sweet when it is tasted.
Active Voice: Rice sells cheap.
Passive Voice: Rice is cheap when it is sold.
Active Voice: The house is building.
Passive Voice: The house being built.
Active Voice: The rose smells sweet.
Passive Voice: The rose is sweet when it is smelt.
***Reflexive Object, Factitive Object and Adverbial Object are never used as Subject in Passive Voice.
Active Voice: He killed himself.
Passive Voice: He was killed by himself. ( Himself was killed by him is a wrong sentence)
Active Voice: He hurt himself.
Passive Voice: He was hurt by himself.
Active Voice: We made him captain.
Passive Voice: He was made captain by us.
Active Voice: Karim worked ten hours.
Passive Voice: Ten hours taken by Karim in working.
Sometimes Passive Voice is better than Active Voice
Example:- He was born in Rajshahi.
The tigers are found in the zoo.