Changing Active Voice to Passive voice

Interrogative Type:

Interrogative sentences when in active voice seems much difficult to convert into passive voice.

Because most of the people could not classify the sentence

So it  becomes too difficult to convert into passive voice without understanding the question

When a assertive sentence is asked to convert into passive voice,

We can make it possible by different methods of converting

But when it comes to interrogative

It looks much confusious

For example:

Case-1:

"I bought a car"

Can be changed into passive by the rules we know well

So the answer is" a car is bought by me"

Case-2:

When it comes in the case of interrogative

Let's see what happens

"Who bought this car?"

Here the sentence is lacking the subject which is the most important part of a sentence to get converted into passive voice

So people try to say "that's impossible and the question is given wrong"

Methods of converting a active interrogative sentence to passive:

1) First of everything

Let us know.a logical manner 

An interrogative sentence which is lacking a subject can be changed into assertive by considering some variable in place of 'wh'

Ex:

'Who bought this car?'

So according to our given rule

It can be written as

"X" bought this car.

2) secondly it can be transformed into passive as we have already made an assertive sentence with the given interrogative sentence

Ex:

A.v:      X bought this car

P.v:      this car is bought by X

3) Next

The sentence is made into question tag form (yes or no form) 

So for that the prepositions are brought to the beginning of the sentence

Ex: Is this car bought by X?

4) Now 'by' prefixed to 'who' (from the original sentence)

Is changed to 'whom' and added to beginning of the sentence 

So the final Answer is 

"By whom is this car bought?"

So every type of interrogative sentence can be change just like this

With small changes according to the sentence using these 4 logical steps

Exercise:

You can try converting the following questions

1)who teaches you English?

2)what happened to your leg yesterday?

3)where is the railway station?

4)How much the pen costs?

5)which is the best among those books?

6)when will the train arrive?