exercises at page 239 from grammar in progress 

1. doesn’t have to
2. didn’t you have to
3. didn’t need to
4. don’t need to
5. could you
6. needn’t have sent
7. don’t have to 
8. couldn’t

1. obbligo esterno
2. deduzione positiva nel presente
3. obbligo interno nel presente
4. divieto assoluto nel passato
5. proposta gentile nel presente
6. assenza di necessità nel passato
7. proposta gentile nel presente
8. raccomandazione nel presente

1. your mom is not fine. you must help her!
2. they must study now! you mustn’t disturb them 
3. you don’t have to eat if you don’t have to 
4. i had a fat tyre, that’s why i had to change it
5. i needn’t have to download a program on my laptop
6. during industrial revolution lots of kids had to work in factories
7. silvia’s shop is going great, she must be happy and relieved
8. what shoes should i wear? you should put comfy shoes to dance