1.The person who painted that must have been a very great artist.
Only a very great artist could paint that
2.This damage to your car may not be so easily repaired.
It is not easy to repair your damage car.
9.We could find neither a bed nor a couch,the hotel was so full.
It was impossible to find a bed or a couch in the hotel.
13.There must be somebody at home.
There can’t nobody at home.