Question Detail

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.

1. Who taught you English ?

By who were you taught English.
By which were you taught English.
By whom you were taught English ?
By whom were you taught English ?

Answer: Option D

2. He stole that watch.

That watch was stolen by him.
That watch stolen by him.
That watch stole by him.
That watch had stolen by him.

Answer: Option A

Explanation:

Note : Rule to make active voice of Simple Past Tense :

Passive subject + was/were + third form of verb + by + passive object

3. We hate him.

He has hated by us.
He is hated by us.
He was hated by us.
He will hated by us.

Answer: Option B

4. After driving Professor Jones to the museum she dropped him at his hotel.

After she was driven Professor Jones to the museum she had dropped him at his hotel.
After she had driven Professor Jones to the museum she had dropped him at his hotel.
Professor Jones was being driven dropped at his hotel.
After being driven to the museum, Professor Jones was dropped at his hotel.

Answer: Option D