I. 1. get to

   2. think of

   3. go out

   4. come true

   5. strict

II. 1. Can

    2. can’t

    3. must

    4. have to

III. One possible version:

School rules are very important. There are many rules in our school. For example, we must wear school uniform. We should go to school on time. We have to keep the classroom tidy and clean, and we must be quiet in the library. These are the rules we have to follow. Besides, there are lots of things we can’t do at school. For example, we can’t eat or sleep in class. Don’t fight in the school and we mustn’t bring mobile phones into the classroom. We can’t go out at night.