1.Your hair needs cutting.(should)
You..........cut.
2.I doubt very much that you saw Carla at the party as she's in Scotland at the moment.(can't)
You..........Carla at the party as she's in Scotland at the moment.
3.It wasn't necessary to meet me at the airport yesterday.(needn't)
You..........me at the airport yesterday.
1.Your hair needs cutting.(should)
You should have your hair cut.
2.I doubt very much that you saw Carla at the party as she's in Scotland at the moment.(can't)
You can't have seen Carla at the party as she's in Scotland at the moment.
3.It wasn't necessary to meet me at the airport yesterday.(needn't)
You needn't have met me at the airport yesterday.
1.Your hair needs cutting.(should)
You should have your hair cut.
2.I doubt very much that you saw Carla at the party as she's in Scotland at the moment.(can't)
You can't have seen Carla at the party as she's in Scotland at the moment.
3.It wasn't necessary to meet me at the airport yesterday.(needn't)
You needn't have met me at the airport yesterday