Question Detail

We ought to have saved our environment.

Our environment ought to had been saved.
Our environment ought to have been save.
Our environment ought to have been saved.
Our environment ought to have saved.

Answer: Option C

1. They are not playing the game.

The game has not being played by them.
The game is not being played by them.
The game is being not played by them.
The game has being not played by them.

Answer: Option B

2. Don't insult the deaf man.

Let the deaf man not be insult.
Let the deaf man not be insulted.
Let the deaf man not insulted.
Let deaf man not be insulted.

Answer: Option B

3. 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.