Question Detail

We crowned him leader.

He had crowned leader.
He crown leader.
He was crowned leader.
He crowned leader.

Answer: Option C

1. My mother is cooking food.

Food is being cooked by my mother.
Food has been cooked by my mother.
Food was being cooked by my mother.
Food is being cook by my mother.

Answer: Option A

2. Switch on the cooler.

Let cooler be switch on.
Switch on the cooler please.
Let cooler be switched on.
Let the cooler be switched on.

Answer: Option D

3. Where do they buy the utensils ?

Where did the utensils bought ?
Where was the utensils bought ?
Where are the utensils bought ?
Where were the utensils bought ?

Answer: Option C

Explanation:

It can also be :
Where are the utensils bought by them ?

4. We must have obeyed our teachers.

Our teachers might have obeyed.
Our teachers might have been obeyed.
Our teachers must have been obeyed.
Our teachers must have obeyed.

Answer: Option C

Explanation:

If we have "Subject + Modal Auxiliary verb + have + third verb + object"
then we change it to

Passive subject + Modal Auxiliary verb + have been + third form + by + passive object.

Modal Auxiliary verb are : can, could, shall, will, may, might, should, would, must, ought to etc.