1. Of Ability and Possibility
1.1. Must, may, might, can't and couldn't are used with a present perfect verb form to show how certain a speaker is that a past situation happened or didn't happen.
1.2. Modal Verb + Base Verb May/Might/Could/Must + Base Verb
1.2.1. MAY: Present: Where are my keys? They may be in the car. Future: I may go to the party tonight.
1.2.2. MIGHT: Where are my keys? They might be in the car. I might go to the party tonight.
1.2.3. COULD: Present: Where are my keys? They could be in the car. Future: We could go to the party tonight.
1.2.4. MUST: Everyone is wearing a jacket. It must be cold
1.2.5. CAN: Can I got to the bathroom please?
2. Of Advice and Criticism
2.1. They are used primarily to give or ask for advice. These modal verbs are should and ought to.
2.2. We use should/ought to+have+past participe to express criticism.
2.2.1. You shouldn't have got out of bet
2.2.2. You ought to have used this oinment
2.3. AFFIRMATIVE: Subject + should + infinitive NEGATIVE: Subject + shouldn't ought not + infinitive
2.3.1. You should go and see your grandmother once a week.
2.3.2. With this temperature you ought to visit the doctor.
2.3.3. They shouldn't take that train, it doesn't stop in Madrid.
2.3.4. You ought not to spend so much money.
3. Of Prohibition
3.1. These situations are the opposite of giving permission. This modal verbs for prohibition lesson shows you how to use may and can to prohibit someone or create rules
3.2. The modal verbs used are May and Can. They are used as negatives:
3.3. Can’t
3.3.1. You can’t drive here.
3.4. Must not
3.4.1. You must not play music.
3.5. May not
3.5.1. You may not smoke in this house.
4. Of Obligation and Necessity
4.1. Those that primarily express a firm obligation or necessity - must and have to
4.2. AFFIRMATIVE: Subject + must + infinitive NEGATIVE: Subject + must not / mustn't + infinitive
4.2.1. I must study every day for my exam.
4.2.2. You mustn't shout at your brothers.
4.3. PRESENT : Affirmative: Subject + have / has to + infinitive Negative: Subject + don't / doesn't + have to + infinitive
4.3.1. You have to do sport every day.
4.3.2. You don't have to do sport every day.
4.4. PAST: Affirmative:Subject + had to + infinitive Neggative: Subject + didn't + have to + infinitive
4.4.1. I didn't have to go to the hospital yesterday.
4.4.2. I had to go to the hospital yesterday
5. Of Deduction
5.1. They are used to express deduction and contention.
5.2. We use must or can't to show that we are almost certain that something is or is not true.
5.2.1. He must be rich
5.2.2. He can't be ill; he's out jogging.
5.3. We use must/can't +have+past participe to talk about the past.
5.3.1. She must have had some bad news.
5.3.2. They can't have seen. Dad; he is in hospital.