In active voice the subject performs the action, while in passive voice the subject receives the action. If a sentence does not have an object it can not be transformed into a passive voice.
Active Voice: Subject + Verb + Object
John plays cricket.
Passive Voice: Object + be (helping verb) + Past Participle (3rd form of the verb) + by + Subject
Cricket is played by John.
He writes a story.
A story is written by him.
She does not like green vegetables.
Green vegetables are not liked by her.
Do you love him?
Is he loved by you?
Does your friend support you?
Are you supported by your friend?
Why do you scold children?
Why are children scolded by you?
She is writing a story.
A story is being written by her.
We are not buying a new house.
A new house is not being bought by us.
Are you taking interest in this work?
Is interest being taken in this work by you?
Is he learning many languages?
Are many languages being learnt by him?
When are they returning your money?
When is your money being returned by them?
I have left that job.
That job has been left by me.
We have not taken decision.
Decision has not been taken by us.
Has he promised you?
Have you been promised by him?
Have your teachers checked your copies?
Have your copies been checked by your teachers?
Which toy have you purchased for him?
Which toy has been purchased for him by you?