Modal/ Semi-modal

1. Don't have to/ didn't have to

1.1. Lack of obligation

2. We use modal verbs to modify the meaning of the main verb.

2.1. Can/could

2.1.1. Ability, permission, request, advice

2.2. Will/Shall

2.2.1. Future/ willingness/ promises and offers/ conditional sentences

2.3. May / might / could

2.3.1. Possibility/ permission

2.4. Would / would have

2.4.1. Requests/ past of will/ conditional sentences/ habits

2.5. Must / Mustn't

2.5.1. Rules/ obligation

2.6. Should /Shouldn't

2.6.1. Recommendation/ advice

2.7. Should have / Shouldn't have

2.7.1. Regret/ criticism

2.8. Needn't (Needn't have

2.8.1. Lack of obligation

2.9. May be / Might be / Must be / Can't + be / + be -ing form

2.9.1. Speculation about the present

2.10. May have / Might have / must have / can't have + past participle / + been -ing form

2.10.1. Speculation about past

2.11. Could have / Couldn't have

2.11.1. Possibility in the past/ critisism

2.12. Will have

2.12.1. Future completion

3. Semi-modal verbs have some of the characteristics of modals, but not all.

3.1. Have to/ had to/ have got to

3.1.1. Rules/ obligation

3.2. Ought to

3.2.1. Obligation/ advise

3.3. Need to

3.3.1. Necessity/ instructions/ guidance

3.4. Don't need to/ didn't need to

3.4.1. Lack of obligation

3.5. Would like/ would like to

3.5.1. Offers/ invitations/preferences

3.6. Be able to

3.6.1. Ability/ infinitive of can