Fill in the gaps.Use must or have to in the positive or negative form.
1. If you want to make progress,you....work regularly.
2.You....open window. If May fall.
3. I....eat more vegetables and fruit.They are good for me.
4. You....pay for this book.It's a present.
5. You....interrupt your teacher.
6. You grandmother....work. Her husband had earned enough money.