I. 1. She will come soon if you call on her. 2. There will be no sound if they keep quiet. 3. What can you do if your friend doesn't show up?
II. 1. What would you do unless he came? 2.If I were her, I would go on searching for the truth. 3. If only Mary came sooner! 4. Unless the kids stayed put, the pursuer would see them!
III. 1.Had I been there on time, they wouldn't have left the house! 2. They couldn't have done such a thing unless they had been told to (do that) . 3. If the phone had not rung, she wouldn't have answered. 4. I should have thought better if I had wanted that be a success!