Modals of Obligation

1. Must

1.1. Advice

1.2. personal opinion

1.3. Stronger than should

1.4. exp. You must see a doctor

2. Should

2.1. advice

2.2. personal opinion

2.3. less strong that (must)

2.4. exp: You should sleep early

3. Have to

3.1. general rule or law

3.2. not an opinion

3.3. exp. You have to wear a seat belt