G
1. couldn't
2. had to
3. mustn't
4. could
5. should
H
1. Can I use your laptop?
2. You shouldn't give your personal information online.
3. I must buy a new fridge.
4. You mustn't talk in the library.
5. We couldn't chat online while we were in Warsaw.
I
1. the friendliest
2. more comfortable
3. the biggest
4. the worst
5. taller
