Modal Verbs

1. Prohibition

1.1. Mustn't

1.2. Don't have to

2. Ability

2.1. Can

2.2. Can't

2.3. Could

3. Deduction

3.1. 50%Sure

3.1.1. Might

3.1.2. May

3.1.3. Could

3.2. 100% Sure

3.2.1. Must

3.2.2. Can't

4. Permission

4.1. Can

4.2. Allowed

5. Advice

5.1. Should

5.2. Shouln't

5.3. Ought to

6. Possibility

6.1. Might

6.2. May

7. Obligation

7.1. Must

7.2. Have to

8. Necessity

8.1. Have to

8.2. Need

8.3. Needn't

9. Absence of Obligation

9.1. Needn't

9.2. Must

10. Pattern: Modal verb + Infinitive