1. Obligation
1.1. Should/Ought to
1.1.1. Obligation
1.1.2. Giving advice
1.1.3. Recommendations
1.1.4. Say what we think is a good idea
1.1.5. Impossibility
1.1.6. We plan or expect sth to happend
1.2. Shouldn't
1.2.1. If sth is unlikely
2. Conclusions, willingness, habitual events.
2.1. Will
2.1.1. Draw conclusions
2.1.2. Draw assumptions about sth we think is true
2.1.3. (Un)Willingness of refusal to so sth
2.1.3.1. we use: will not
2.1.4. Sth is necessary in fuure
2.2. Would
2.2.1. Willingness in future
2.2.2. In conditionals
2.2.3. Characteristic behaviour
2.2.3.1. Habits
2.2.3.2. things that are true
2.2.4. Don't use: willingness on a specific occasion in past
2.2.5. Don't use: to talk about past states
2.3. Used to
2.3.1. Things that happened repeatedly in the past
3. Not necessary
3.1. Didn't need to Didn't have to
3.1.1. It was not necessary to do sth in the past
3.2. Needn't have
3.2.1. Sth was done in the past and was not necessary
4. Ability
4.1. Be able to
4.1.1. Formal context
4.1.2. Ability on a specific occasion (past)
4.1.3. Negative in the past
4.1.4. Perfect tenses
4.1.4.1. -ing
4.1.4.2. infinitive
4.1.4.3. after modal verbs
4.1.5. Future ability
4.2. Can/Could
4.2.1. Les formal
4.2.2. With verbs of sense
4.2.2.1. feel
4.2.2.2. hear
4.2.2.3. see
4.2.3. With verbs of thinking
4.2.3.1. believe
4.2.3.2. remember
4.2.3.3. understand
4.2.4. With passives