1. ASSUMPTIONS
1.1. PRESENT
1.1.1. wil+inf
1.1.2. must/have (got) to
1.1.3. should/ought to
1.2. PAST
1.2.1. will + have + papa
1.2.2. would + have + papa
1.2.2.1. imaginary situation
1.2.3. must + have + papa/been + -ing
1.2.4. must have had to
1.2.4.1. assumption containing an obligation
2. OBLIGATION
2.1. formal rules
2.1.1. must/mustn't
2.1.1.1. Use with care!
2.2. intentions
2.2.1. must
2.3. questions for which you expect a negative answer
2.3.1. must we/have we got to/ do we have to?
2.4. authority outside the speaker
2.4.1. have (got) to
2.4.2. should
2.5. absence of obligation
2.5.1. needn't
2.5.1.1. with typical verbs in the negative
2.5.1.2. with typical adverbs
2.5.1.3. in formal questions
2.5.1.4. speaker's decision/permission
2.5.2. don't need to
2.5.2.1. in questions
2.5.2.2. general necessity
2.5.3. don't have to
2.6. recommendations
2.6.1. should
2.6.1.1. for general recommendations
2.6.1.2. for advice with "I'
2.6.1.3. in WH-questions
2.6.2. ought to
2.6.2.1. spoken Eng.
2.6.3. had better
2.6.3.1. also used to express desperate hope or warnings (sp. Eng.)
2.6.3.2. not for general recommendations
2.7. offers
2.7.1. Should I?
2.7.2. Shall I?
3. PERMISSION
3.1. PRESENT
3.1.1. can
3.1.2. be allowed to
3.1.3. May I/we?
3.1.3.1. in formal questions
3.1.3.2. offers
3.2. PAST
3.2.1. could
3.2.1.1. general permission
3.2.2. was/were allowed to
3.2.2.1. particular permission
3.2.3. couldn't or wasn't/weren't allowed to
3.2.3.1. interchangeable
4. ABILITY
4.1. PRESENT
4.1.1. can
4.1.1.1. as we speak
4.1.1.2. before passive voice
4.1.1.3. know how to
4.1.2. be able to
4.1.3. could
4.1.3.1. idea of condition
4.1.3.2. request
4.2. PAST
4.2.1. could
4.2.1.1. negative sentences
4.2.1.2. verbs of thinking & perception
4.2.1.3. with "the only time/place..", "all" or "hardly, almost, nearly, just"
4.2.2. was/were able to/managed to
4.2.2.1. single past achievement
5. POSSIBILITY/PROBABILITY
5.1. FUTURE
5.1.1. can
5.1.1.1. real possibility in the future
5.1.2. can't
5.1.2.1. theoretical & actual possiblity
5.1.3. could
5.1.3.1. (less likely) possibility
5.1.4. may/might/could + have + papa
5.2. PRESENT
5.2.1. may
5.2.1.1. formal, academic discourse
5.2.2. might
5.2.2.1. spoken Eng.
5.2.3. could
5.3. PAST
5.3.1. may/might/could have + papa
5.3.2. may/might/could have been +-ing
5.3.2.1. to criticise sby
6. HABITS & GENERAL TRUTHS
6.1. PRESENT
6.1.1. wil
6.1.1.1. also used to express criticism
6.1.1.2. if you will
6.2. PAST
6.2.1. might/could + inf
6.2.2. would + inf
6.2.2.1. also used to criticise sby
6.2.3. would/used to
6.2.3.1. not for
6.2.3.1.1. particular situations
6.2.3.1.2. an exact number of times
6.2.3.1.3. a completed action in the past
6.2.3.2. wouldn't/
6.2.3.2.1. also for particular situations