1. HAVE TO
1.1. Examples
1.1.1. AFIRMATIVE
1.1.1.1. I have to work on Sundays
1.1.2. NEGATIVE
1.1.2.1. You needn’t go to school at weekends
1.1.3. INTERROGATIVE
1.1.3.1. Do you have to get your passport?
2. DEFINITION
2.1. An auxiliary verb that expresses necessity or possibility. English modal verbs include must, shall, will, should, would, can, could, may, and might.
3. THE FOLLOWING ARE MODAL VERBS:
3.1. CAN
3.1.1. Hability,Request,Possibility/Impossibility
3.2. SHOULD
3.2.1. Advice,Opinion
3.3. COULD
3.3.1. Past ability, Polite request,Polite suggestion ,Possibiliy
3.4. MIGHT
3.4.1. Possibility
3.5. MUST
3.5.1. Obligation, necessity, deduction; in the negative form - prohibition
3.6. OUGHT TO
3.6.1. Advice saying what is the right thing to do
3.7. BE ABLE TO
3.7.1. Hability and opportunity in the past, presentor future
3.8. HAVE TO
3.8.1. Obligation ,necessity
3.9. MAY
3.9.1. Permission (formal),Polite request,Possibility
4. CARACTERISTICS
4.1. They never change their form. You can't add "s", "ed", "ing"
4.2. They are always followed by an infinitive without "to" (e.i. the bare infinitive.)
4.3. They are used to indicate modality allow speakers to express certainty, possibility, willingness, obligation, necessity, ability
5. GRAMATICAL FORM
5.1. Afirmative form
5.1.1. .
5.2. Negative form
5.2.1. .
5.3. Interrogative form
5.3.1. .
6. SHOULD
6.1. Examples
6.1.1. AFIRMATIVE
6.1.1.1. You should accept the job
6.1.2. NEGATIVE
6.1.2.1. You shouldn’t go to the concert because you have a lot of homework.
6.1.3. INTERROGATIVE
6.1.3.1. Should we tell him the news?
7. MUST
7.1. Examples
7.1.1. AFIRMATIVE
7.1.1.1. We must be in the meeting next week.
7.1.2. NEGATIVE
7.1.2.1. They mustn't go to the party.
7.1.3. INTERROGATIVE
7.1.3.1. Must you speak English in class?