Modals of obligation

Hello! A new moth and we are getting closer to the end of this school year. But before that happens, we still have time to improve our skills before the final exams. I have seen how difficult has been for you to get the knack of modal verbs expressing obligation. For that reason, I've been searching the net to provide you with some extra material that could help you.

1. If you follow this link, it will take you to a multiple-choice exercise on Englishclub.com. This place also provides with a wide range of exercises and grammar explanations which can be really handy.
2. This other link will lead to a different site but the purpose is the same to help you with the modals of obligation.

Hope you find them both useful.