Question Detail

They had not done their tasks.

Their tasks had not been done.
Their tasks had been not done.
Their tasks have not been done.
Their tasks have been not done.

Answer: Option A

1. Rahul made her laugh.

She had made to laugh by Rahul.
She was made for laugh by Rahul.
She was made to laugh by Rahul.
She was made laugh by Rahul.

Answer: Option C

Explanation:

Note : Please note "made to laugh"

2. Who is creating this mess?

By whom this mess is being created?
By whom is this mess being created?
Who has been created this mess?
By whom has this mess been created?

Answer: Option B

3. Did he buy a car ?

Was a car bought by him.
Did car bought by him.
Did a car bought by him.
Were a car bought by him.

Answer: Option A

4. Someone has stolen his book.

His book is been stolen.
His book has been stolen.
His book is stolen.
His book has stolen.

Answer: Option B

Explanation:

Apart from Rule to make active voice of Present Perfect Tense, which is

Passive subject + has/have + been + third form of verb + by + passive object

Please also note that words like, "someone", "somebody", "people", "police", "public" etc are dropped. But in rare cases we can use them if sentence meaning is not clear.